IS-875-ALL-IN-ONE

IS : 875 (Part 1) - 1987( Incorporating IS : 1911-1967 )

(Reaffirmed 1997)Edition 3.1

(1997-12)

Indian Standard

C O D E O F P R A C T IC E FO RD E SIG N L O A D S (O T H E R TH A N E A R TH Q U A K E )

F O R B U IL D IN G S A N D STR U C TU R E SPART 1 DEAD LOADS — UNIT WEIGHTS OF BUILDING MATERIALS AND

STORED MATERIALS

( Second Revision )(Incorporating Amendment No. 1)

UDC 624.042 : 006.76

© BIS 2002

B U R E A U O F I N D I A N S T A N D A R D SMANAK BHAVAN, 9 BAHADUR SHAH ZAFAR MARG

NEW DELHI 110002

Price Group 12

IS : 875 (Part 1) - 1987

1

C O N T E N T S

PAGE

0. FOREWORD 3

1. SCOPE 4

2. BUILDING MATERIALS 4

TABLE 1 UNIT WEIGHT OF BUILDING MATERIALS

1. Acoustical material 42. Aggregate, coarse 43. Aggregate, fine 44. Aggregate, organic 45. Asbestos 46. Asbestos cement building pipes 47. Asbestos cement gutters 58. Asbestos cement pressure pipes 59. Asbestos cement sheeting 5

10. Bitumen 511. Blocks 512. Boards 513. Bricks 614. Brick chips and broken bricks 615. Brick dust ( SURKHI ) 616. Cast iron, manhole covers 717. Cast iron, manhole frames 718. Cast iron pipes 719. Cement 720. Cement concrete, plain 721. Cement concrete, prestressed 822. Cement concrete, reinforced 823. Cement concrete pipes 824. Cement mortar 825. Cement plaster 826. Cork 827. Expanded metal 828. Felt, bituminous for waterproofing and damp-proofing 929. Foam slag, foundry pumice 930. Glass 931. Gutters, asbestos cement 932. Gypsum 933. Iron 934. Lime 935. Linoleum 1036. Masonry brick 1037. Masonry, stone 1038. Mastic asphalt 1039. Metal sheeting, protected 1040. Mortar 1041. Pipes 1142. Plaster 1643. Sheeting 1644. Slagwool 17

IS : 875 (Part 1) - 1987

2

PAGE

45. Soils and gravels 1746. Steel sections 1747. Stone 2548. Tar, coal 2549. Thermal insulation 2550. Terra cotta 2651. Terrazzo 2652. Tiles 2653. Timber 2654. Water 2855. Wood-wool building slabs 28

3. BUILDING PARTS AND COMPONENTS

TABLE 2 UNIT WEIGHTS OF BUILDING PARTS OR COMPONENTS

1. Ceilings 292. Cement concrete, plain 293. Cement concrete, reinforced 294. Damp-proofing 295. Earth filling 296. Finishing 297. Flooring 298. Roofing 309. Walling 31

4. STORE AND MISCELLANEOUS MATERIALS 31

APPENDIX A UNIT WEIGHTS OF STORE AND MISCELLANEOUS MATERIALS

1. Agricultural and food products 322. Chemicals and allied materials 333. Fuels 334. Manures 345. Metals and alloys 346. Miscellaneous materials 367. Ores 378. Textiles, paper and allied materials 37

IS : 875 (Part 1) - 1987

3

Indian StandardC O D E O F PR A C TICE FO R

D ESIG N LO A D S (O TH E R TH A N E AR TH Q U A K E ) FO R BU ILD IN G S A N D STR U C TU R E S

PART 1 DEAD LOADS — UNIT WEIGHTS OF BUILDING MATERIALS AND STORED MATERIALS

( Second Revision )0. F O R E W O R D

0.1 This Indian Standard (Part 1) (SecondRevision) was adopted by the Bureau of IndianStandards on 30 October 1987, after the draftfinalized by the Structural Safety SectionalCommittee had been approved by the CivilEngineering Division Council.

0.2 A building has to perform m any functionssatisfactorily. Am ongst these functions are theutility of the building for the intended use andoccupancy, structural safety, fire safety; andcom pliance w ith hygienic, sanitation, ventilationand daylight standards. The design of thebuilding is dependent upon the m inim umrequirem ents prescribed for each of the abovefunctions. The m inim um requirem entspertaining to the structural safety of buildingsare being covered in this code by w ay of layingdow n m inim um design loads w hich have to beassum ed for dead loads, im posed loads, snowloads and other external loads, the structurew ould be required to bear. S trict conform ity toloading standards recom m ended in this code, it ishoped, w ill not only ensure the structural safetyof the buildings w hich are being designed andconstructed in the country and thereby reducethe hazards to life and property caused by unsafestructures, but also elim inate the w astage causedby assum ing unnecessarily heavy loadings.

0.3 This Indian Standard code of practice wasfirst published in 1957 for the guidance of civilengineers, designers and architects associatedw ith planning and design of buildings. Itincluded the provisions for the basic design loads(dead loads, live loads, w ind loads and seism icloads) to be assum ed in the design of buildings.In its first revision in 1964, the w ind pressureprovisions w ere m odified on the basis of studiesof w ind phenom enon and its effect on structures,undertaken by the special com m ittee inconsultation w ith the Indian M eteorologicalD epartm ent. In addition to this, new clauses onw ind loads for butterfly type structures wereincluded; w ind pressure coefficients for sheetedroofs both curved and sloping, were m odified;seism ic load provisions were deleted (separatecode having been prepared) and m etric system of

w eights and m easurem ents w as adopted.

0.3.1 With the increased adoption of the code, anumber of comments were received onprovisions on live load values adopted fordifferent occupancies. Simultaneously, live loadsurveys have been carried out in America andCanada to arrive at realistic live loads based onactual determination of loading (movable andimmovable) in different occupancies. Keepingthis in view and other developments in the fieldof wind engineering, the Sectional Committeeresponsible for the preparation of the standardhas decided to prepare the second revision inthe following five parts:

Part 1 Dead loadsPart 2 Imposed loadsPart 3 Wind loadsPart 4 Snow loadsPart 5 Special loads and loads

combinationsEarthquake load is covered in a separate

standard, namely IS : 1893-1984* which shouldbe considered along with the above loads.0.4 This standard deals with dead loads to beassumed in the design of buildings and same isgiven in the form of unit weight of materials.The unit weight of other materials that arelikely to be stored in a building are alsoincluded for the purpose of load calculationsdue to stored materials.0.4.1 This standard incorporates IS : 1911†published in 1967. The unit weight of materialsincorporated in this standard are based oninformation available through published IndianStandards and various other publications.0.4.2 This edition 3.1 incorporates AmendmentNo. 1 (December 1997). Side bar indicatesmodification of the text as the result ofincorporation of the amendment.0.4.3 The values given in this standard have beenrounded off in accordance w ith IS : 2 - 1960‡.

*Criteria for earthquake resistanT design of structures( third revision ).

†Schedule of unit weights of building materials ( firstrevision ).

‡Rules for rounding off numerical values ( revised ).

IS : 875 (Part 1) - 1987

4

1. SCOPE

1.1 This code (Part 1) covers unit weight/massof materials, and parts or components in abuilding that apply to the determination ofdead loads in the design of buildings.1.1.1 The unit weight/mass of materials thatare likely to be stored in a building are alsospecified for the purpose of load calculationsalong with angles of internal friction asappropriate.

NOTE 1 — Table 1 gives the unit weight mass ofindividual building materials in alphabetical order;Table 2 covers the unit weight mass of parts orcomponents of a building; and Appendix A gives unitweight mass of stored materials.

2. BUILDING MATERIALS

2.1 The unit weight/mass of materials used inbuilding construction are specified in Table 1.

TABLE 1 UNIT WEIGHT OF BUILDING MATERIALS

MATERIAL NOMINAL SIZE OR THICKNESS

WEIGHT/MASS

mm kN kg per

(1) (2) (3) (4) (5)

1. Acoustical Material

EelgrassGlass fibreHairMineral woolSlag woolCork

10101010——

5.70 × 10–3 to 7.65 × 10–3

3.80 × 10–3

19.10 × 10–3

13.45 × 10–3

2.652.35

0.58 to 0.780.391.951.37270240

m2

,,,,,,

m3

,,

2. Aggregate, Coarse

Broken stone ballast:Dry, well-shakenPerfectly wetShingles, 3 to 38 mm

Broken bricks:FineCoarseFoam slag (foundry pumice)Cinder*

———

————

15.70 to 18.3518.85 to 21.95

14.35

14.209.906.857.85

1 600 to 1 8701 920 to 2 240

1 460

1 4501 010

700800

,,,,,,

,,,,,,,,

3. Aggregate, Fine

Sand:Dry, cleanRiverWetBrick dust ( SURKHI )

————

15.10 to 15.7018.0517.25 to 19.609.90

1 540 to 1 6001 840

1 760 to 2 0001 010

,,,,,,,,

4. Aggregate, Organic

Saw dust, loosePeat:

DrySandy, compactWet, compact

—

———

1.55

5.50 to 6.307.85

13.35

160

560 to 640800

1 360

,,

,,,,,,

5. Asbestos

FeltFibres:

PressedSprayed

NaturalRaw

10

—10——

0.145

9.400.02

29.805.90 to 8.85

15

9602

3 040600 to 900

m2

m3

m2

m3

,,

6. Asbestos Cement Building Pipes( see under 41 ‘Pipes’ in this table )

*Also used for filling purposes.

( Continued )

IS : 875 (Part 1) - 1987

5

TABLE 1 UNIT WEIGHT OF BUILDING MATERIALS — Contd


WEIGHT/MASS

mm kN kg per

(1) (2) (3) (4) (5)

7. Asbestos Cement Gutters[ see IS : 1626 (Part 2)-1980* ]

Boundry wall gutters:400 × 150 × 250 mm450 × 150 × 300 mm300 × 150 × 225 mm275 × 125 × 175 mm

Valley gutters:900 × 200 × 225 mm600 × 150 × 225 mm450 × 125 × 150 mm400 × 125 × 250 mm

Half round gutters:150 mm250 mm300 mm

12.512.512.510.0

12.512.512.512.5

9.59.59.5

0.160.160.130.085

0.2450.1600.1450.130

0.0430.0790.087

16.016.013.08.5

24.816.114.613.2

4.48.18.9

m,,,,,,

,,,,,,,,

,,,,,,

8. Asbestos Cement Pressure Pipes

( see under 41 ‘Pipes’ in this table )

9. Asbestos Cement Sheeting( See IS : 459-1970† )

Corrugated (pitch = 146 mm)Semi-corrugated (pitch = 340 mm)Plain

665

0.118 to 0.1300.118 to 0.1270.09

12.0 to 13.312.0 to 13.09.16

m2

,,,,

10. Bitumen — 0.102 10.40 m3

11. Blocks

Lime-based solid blocks( see IS : 3115-1978‡ )

Hollow (open and closed cavity concrete blocks)[ see IS : 2185 (Part 1)-1979§ ]

Grade A(load bearing)

Grade B(load bearing)

Grade C(non-load bearing)

Solid concrete blocks

—

—

—

—

—

8.65 to 12.55

1.41

1.41 to 0.94

1.41 to 0.94

17.65

880 to 1 280

144

144 to 96

144 to 96

1 800

,,

,,

,,

,,

,,

12. Boards

Cork boards:CompressedOrdinary

Fibre building boards( see IS : 1658-1977|| )

1010

0.040.02

42

m2

,,

Medium hardboard68

1012

0.028 to 0.0470.038 to 0.0630.047 to 0.0780.056 to 0.095

2.88 to 4.803.84 to 6.404.80 to 8.005.76 to 9.60

,,,,,,,,

*Specification for asbestos cement building pipes and pipe fittings, gutters and gutter fittings and roofing fittings:Part 2 Gutters and gutter fittings ( first revision ).

†Specification for unreinforced corrugated and semi-corrugated asbestos cement sheets ( second revision ).‡Specification for lime based block ( first revision ).§Specification for concrete masonry units: Part 1 Hollow and solid concrete blocks ( second revision ).||Specification for fibre hardboards ( second revision ).

( Continued )

IS : 875 (Part 1) - 1987

6



WEIGHT/MASS

mm kN kg per

(1) (2) (3) (4) (5)

Standard hardboard345

0.024 to 0.0350.031 to 0.0470.039 to 0.059

2.40 to 3.603.20 to 4.804.00 to 6.00

m3

,,,,

Tempered hardboard

Fire insulation board( see IS : 3348-1965* )

Fibre insulation board, ordinaryor flame-retardant type, bitumen-bounded fibreinsulation board

6 99

121825

0.047 to 0.0710.071 to 0.1060.0350.0470.0710.098

4.80 to 7.207.20 to 10.803.64.87.2

10.0

,,,,,,,,,,,,

Gypsum plaster boards( see IS : 2095-1982† )

Insulating board (fibre)Laminated board (fibre)

9.512.515126

0.069 to 0.0980.093 to 0.1470.110 to 0.1540.0340.034

7.0 to 10.09.5 to 15.0

11.25 to 15.753.53.5

,,,,,,,,,,

Wood particle boards( see IS : 3087-1985‡ )

Designation:FPSIFPTHXPSOXPTU

Wood particle boards for insulation purposes( see IS : 3129-1985§ )

—————

4.90 to 8.854.90 to 8.854.90 to 8.854.90 to 8.853.90

500 to 900500 to 900500 to 900500 to 900400

m3

,,,,,,,,

High density wood particle boards ( see IS : 3478-1966|| )Type 1, Grade AType 1, Grade BType 2, Grade AType 2, Grade B

————

0.1170.0880.1170.088

129

129

m2

,,,,,,

NOTE 1 — Density of medium hardboard varies from 350 to 800 kg/m3.NOTE 2 — Density of normal hardboard varies from 800 to 1 200 kg/m3.NOTE 3 — Density of tempered hardboard varies according to treatment. The actual value may be had from the

manufacturers.NOTE 4 — All the three types of hardboards are manufactured to width of 1.2 m.

13. Bricks

Common burnt clay bricks( see IS : 1077-1987¶ )

Engineering bricksHeavy duty bricks

( see IS : 2180-1985** )Pressed bricksRefractory bricksSand cement bricksSand lime bricks

—

——

————

15.70 to 18.85

21.2024.50

17.25 to 18.0517.25 to 19.6018.0520.40

1 600 to 1 920

2 1602 500

1 760 to 1 8401 760 to 2 0001 8402 080

m3

,,,,

,,,,,,,,

14. Brick Chips and Broken Bricks( see under 2 ‘Broken bricks’ in this table )

15. Brick Dust ( SURKHI ) — 9.90 1 010 ,,

*Specification for fibre insulation boards.†Specification for gypsum plaster boards ( first revision ).‡Specification for wood particle boards (medium density) for general purposes ( first revision ).§Specification for low density particle boards ( first revision ).||Specification for high density wood particle boards.¶Specification for common burnt clay building bricks ( fourth revision ).**Specification for heavy-duty burnt clay building bricks ( second revision ).

( Continued )

IS : 875 (Part 1) - 1987

7



WEIGHT/MASS

mm kN kg per

(1) (2) (3) (4) (5)

16. Cast Iron, Manhole Covers( see IS : 1726* )

Double triangular (HD)

Circular (HD)

Circular (MD)

Rectangular (MD)Rectangular (LD) :

Single seal (Pattern 1)(Pattern 2)

Double sealSquare (LD) :

Single seal

Double seal

500560500560500560—

———

455610455610

1.161.371.161.370.570.630.78

0.230.150.28

0.130.250.230.36

118140118140586480

231529

13262337

Cover,,,,,,,,,,,,

,,,,,,

,,,,,,,,

17. Cast Iron, Manhole Frames( see IS : 1726* )

Double triangular (HD) 500600

1.091.13

111115

Frame,,

Circular (HD)

Circular (MD)

Rectangular (MD)Rectangular (LD) :

Single seal (Pattern 1)(Pattern 2)

Double sealSquare (LD) :

Single seal

Double seal

500560500560—

———

455610455610

0.831.060.570.630.63

0.150.100.23

0.070.130.150.18

85108586464

151023

7131518

,,,,,,,,,,

,,,,,,

,,,,,,,,

18. Cast Iron Pipes( see under 41 ‘Pipes’ in this table )

19. Cement( see IS : 269-1976† )

Ordinary and aluminousRapid-hardening

——

14.1012.55

1 4401 280

m3

,,

20. Cement Concrete, Plain

AeratedNo-fines, with heavy aggregateNo-fines, with light aggregateWith burnt clay aggregateWith expanded clay aggregateWith clinker aggregateWith pumice aggregateWith sand and gravel or crushed natural

stone aggregateWith saw dustWith foamed slag aggregate

————————

——

7.4515.70 to 18.808.65 to 12.55

17.25 to 21.209.40 to 16.50

12.55 to 17.255.50 to 11.00

22.00 to 23.50

6.30 to 16.509.40 to 18.05

7601 600 to 1 920

880 to 1 2801 760 to 2 160

960 to 1 6801 280 to 1 760

560 to 1 1202 240 to 2 400

640 to 1 680960 to 1 840

,,,,,,,,,,,,,,,,

,,,,

*Specification for cast iron manhole covers and frames.†Specification for ordinary and low heat Portland cement ( third revision ).

(Continued)

IS : 875 (Part 1) - 1987

8



WEIGHT/MASS

mm kN kg per

(1) (2) (3) (4) (5)

21. Cement Concrete, Prestressed(conforming to IS : 1343-1980* )

— 23.50 2 400 m3

22. Cement Concrete, Reinforced

With sand and gravel or crushed natural stone aggregate:With 1 percent steelWith 2 percent steelWith 5 percent steel

———

22.75 to 24.2023.25 to 24.8024.80 to 26.50

2 310 to 2 4702 370 to 2 5302 530 to 2 700

,,,,,,

23. Cement Concrete Pipes( see under 41 ‘Pipes’ in this table )

24. Cement Mortar — 20.40 2 080 ,,

25. Cement Plaster — 20.40 2 080 ,,

26. Cork — 2.35 240 ,,

27. Expanded Metal(conforming to IS : 412-1975† )

Reference No. Size of Mesh, Nominal

SWMmm

LWMmm

123456789

101112131415161718192021222324252627282930313233343536

100100100757575404040404040404025252525202020202020202012.512.512.512.512.512.512.5101010

2502502502002002001151157575

11575

1157575757575605060506050605050405050405040404040

0.0300.0240.0160.0420.0320.0210.0800.0600.0600.0280.0390.0390.0200.0200.0540.0380.0280.0210.0700.0700.0500.0500.0360.0360.0210.0210.0500.0500.0400.0300.0300.0250.0250.0500.0350.028

3.082.471.604.283.292.148.026.176.172.854.014.012.042.045.533.932.812.197.157.155.095.093.633.632.182.185.045.044.003.133.132.502.505.983.592.87

m2

,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,

*Code of practice for prestressed concrete ( first revision ).†Specification for expanded metal steel sheets for general purposes ( second revision ).

( Continued )

IS : 875 (Part 1) - 1987

9



WEIGHT/MASS

mm kN kg per

(1) (2) (3) (4) (5)

Reference No. Size of Mesh, Nominal

SWMmm

LWMmm

3738394041424344

9.59.59.566653

28.528.528.52525252015

0.0500.0280.0200.0740.0480.0380.0500.041

5.192.812.097.554.883.905.014.28

m2

,,,,,,,,,,,,,,

28. Felt, Bituminous for Waterproofing and Damp-proofing( see IS : 1322-1982* )

Fibre base:Type 1 (Underlay)Type 2 (Self-finished felt):

Grade 1Grade 2

Hessian base:Type 3 (Self finished felt):

Grade 1Grade 2

—

——

——

8.34 × 10– 3

21.48 × 10– 3

30.21 × 10– 3

21.87 × 10– 3

35.70 × 10–3

0.85

2.193.08

2.233.64

,,

,,,,

,,,,

NOTE 1 — The weight of untreated based shall be taken as in the dry condition.NOTE 2 — The weights given above are indicative of the total weight of ingredients used in the manufacture of felt andnot of the ingredients determined from a physical analysis of the finished material.

29. Foam Slag, Foundry Pumice — 6.85 700 m3

30. Glass ( see IS : 2835-1977† )

Sheet

2.02.53.04.05.05.56.5

0.0490.0620.0740.0980.1230.1340.167

5.06.37.5

10.012.513.717.0

,,,,,,,,,,,,,,

31. Gutters, Asbestos Cement ( see under 7 ‘Asbestos cement gutter’ in this table )

32. Gypsum

Gypsum mortarGypsum powder

——

11.7513.89 to 17.25

1 2001 410 to 1 760

m3

,,

33. Iron

PigGray, castWhite, castWrought

————

70.6068.95 to 69.9074.30 to 75.7075.50

7 2007 030 to 7 1307 580 to 7 7207 700

,,,,,,,,

34. Lime

Lime concrete with burnt clay aggregate — 18.80 1 920 ,,

*Specification for bitumen felts for waterproofing and damp-proofing ( third revision ).†Specification for flat transparent sheet glass ( second revision ).

( Continued)

IS : 875 (Part 1) - 1987

10



WEIGHT/MASS

mm kN kg per

(1) (2) (3) (4) (5)

Lime mortarLime plasterLime stone in lumps, uncalcinedLime, unslaked, freshly burnt in piecesLime slaked, freshLime slaked, after 10 daysLime, unslaked ( KANKAR )Lime, slaked ( KANKAR )

————————

15.70 to 18.0517.2512.55 to 14.108.60 to 10.205.70 to 6.307.85

11.5510.00

1 600 to 1 8401 7601 280 to 1 440

880 to 1 040580 to 640800

1 1801 020

m3

,,,,,,,,,,,,,,

35. Linoleum ( see IS : 653-1980* )

Sheets and tiles

4.43.22.01.6

0.056 90.040 20.026 50.021 5

5.84.11.72.2

m2

,,,,,,

36. Masonry, Brick

Common burnt clay bricksEngineering bricksGlazed bricksPressed bricks

————

18.8523.5520.4022.00

1 9202 4002 0802 240

m3

,,,,,,

37. Masonry, Stone

CastDry rubbleGranite ashlarGranite rubbleLime stone ashlarMarble dressedSand stone

———————

22.5520.4025.9023.5525.1026.5022.00

2 3002 0802 6402 4002 5602 7002 240

,,,,,,,,,,,,,,

38. Mastic Asphalt 10 0.215 22 m2

39. Metal sheeting, Protected Galvanized Steel Sheets and Plain( see IS : 277-1985† )

Class 1

1.601.261.000.800.63

0.1310.1040.0840.0690.056

13.3110.568.607.035.70

,,,,,,,,,,

Class 2

1.601.251.000.800.63

0.1290.1020.0830.0670.054

13.1610.418.456.885.55

,,,,,,,,,,

Class 3

1.601.251.000.800.63

0.1280.1010.0810.0660.053

13.0110.268.306.735.40

,,,,,,,,,,

Class 4

1.601.251.000.800.63

0.1270.1000.0810.0650.052

12.9410.198.226.665.32

,,,,,,,,,,

40. Mortar

CementGypsumLime

———

20.4011.8015.70 to 18.05

2 0801 2001 600 to 1 840

m3

,,,,

*Specification for linoleum sheets and tiles ( second revision ).†Specification for galvanized steel sheets (plain and corrugated) ( fourth revision ).

( Continued )

IS : 875 (Part 1) - 1987

11



WEIGHT/MASS

mm kN kg per(1) (2) (3) (4) (5)

41. Pipes

Asbestos cement pipes[ see IS : 1626 (Part) 1-1980* ]

50608090

100125150

0.032 to 0.0340.032 to 0.0430.051 to 0.0540.052 to 0.0600.058 to 0.0650.072 to 0.0860.086 to 0.108

3.3 to 3.53.3 to 4.45.2 to 5.55.3 to 6.15.9 to 6.67.3 to 8.88.8 to 11.0

m3

,,,,,,,,,,,,

Asbestos cement pressure pipes ( see IS : 1592-1980† )

5080

100125150200250300

0.0560.0670.0900.1390.1750.2640.3800.539

5.76.89.2

14.217.826.938.855

,,,,,,,,,,,,,,,,

Cast iron Pipes:Rainwater pipes

( see IS : 1230-1979‡ )

Standard overall length 1.8 m with socket

55075

100125150

0.0730.1080.1370.1960.255

7.511.014.020.026.0

pipe,,,,,,,,

Standard overall length 1.5 m with socket

5075

100125150

0.0640.0930.1230.1720.230

6.59.5

12.517.523.5

,,,,,,,,,,

Pressure pipes for water, gas and sewage:a) Centrifugally cast

( see IS : 1536-1976§ )i) Socket and spigot pipes:

Barrel:

Class LA

80100125150200250300350400450500600700750

1.1440.1820.2370.2950.4320.5820.7500.9441.1461.3831.6202.1562.7783.111

14.718.624.230.144.059.376.596.3

116.9141.0165.2219.8283.2317.2

m,,,,,,,,,,,,,,,,,,,,,,,,,,

Class A

80100125150200250300350400450500

0.1570.2010.2590.3260.4720.6370.8241.0301.2621.5301.775

16.020.526.433.248.165.084.0

105.0128.7156.0181.0

,,,,,,,,,,,,,,,,,,,,,,

*Specification for asbestos cement buildings pipes and pipe fittings, gutters and gutter fittings and roofing fittings:Part 1 Pipes and pipe fittings ( first revision ).

†Specification for asbestos cement pressure pipes ( second revision ).‡Specification for cast iron rainwater pipes and fittings ( second revision ).§Specification for centrifugally cast (spun) iron pressure pipes for water, gas and sewage ( second revision ).

( Continued )

IS : 875 (Part 1) - 1987

12



WEIGHT/MASS

mm kN kg per(1) (2) (3) (4) (5)

Class A600700750

2.3673.0563.422

241.4311.6348.9

m,,,,

Class B

80100125150200250300350400450500600700750

0.1720.2160.2810.3520.5110.6920.8961.1221.3681.6571.9292.5783.3173.733

17.322.028.735.952.170.691.4

114.5139.5169.0196.7262.9338.2380.6

,,,,,,,,,,,,,,,,,,,,,,,,,,,,

Sockets for Class LA, Class A and Class B barrels

80100125150200250300350400450500600700750

0.0540.0690.0900.1130.1650.2250.2920.3680.4540.5490.6470.8761.1451.292

5.57.19.2

11.516.822.929.837.546.356.066.089.3

116.8131.7

Socket,,,,,,,,,,,,,,,,,,,,,,,,,,

ii) Flanged pipe with screwed flanges:Barrel:Class A

Class B

80 to 300

80 to 300

Same as for centrifugally cast socket and spigot pipes, Class A

Same as for centrifugally cast socket and spigot pipes, Class B

Flanges for Class A and Class B barrels

80100125150200250300

0.0420.0490.0650.0800.1120.1440.182

4.35.06.68.2

11.414.718.6

Flange,,,,,,,,,,,,

b) Vertically cast socket and spigot pipes( see IS : 1537-1976* )Barrel:

Class A

80to

750


800900

1 0001 1001 2001 500

3.824.655.596.597.67

11.98

389474570672783

1 222

m,,,,,,,,,,

Class B

80to

750


800900

1 0001 1001 2001 500

4.155.076.077.238.35

13.07

423516619739851

1 333

m,,,,,,,,,,

*Specification for vertically cast iron pressure pipes for water, gas and sewage ( first revision ).

( Continued )

IS : 875 (Part 1) - 1987

13



WEIGHT/MASS

mm kN kg per(1) (2) (3) (4) (5)

Socket for Class A and Class B barrels

80to

750

Same as for centrifugally cast socket and spigot pipes, Class A and Class B

800900

1 0001 1001 2001 500

1.451.792.182.603.074.91

147182222265313501

Socket,,,,,,,,,,

c) Sand cast (flanged pipes):Barrel:

Class A

80to

750


800to

1 500

Same as for vertically cast socket and spigot pipes, Class A

Class B

80to

750


800to

1 500

Same as for vertically cast socket and spigot pipes, Class B

Flanges for Class A and Class B Barrels

80100125150200250300350400450500600700750800900

1 0001 1001 2001 500

0.0360.0410.0520.0660.0910.1170.1450.1860.2290.2500.3150.4310.5870.6850.7920.9281.181.381.702.71

3.74.25.36.79.3

12.014.819.423.426.532.144.059.969.880.894.6

120.0139.0173.0276.2

Flange,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,

Concrete pipes ( see IS : 458-1971* )

Class NP1 (unreinforced non-pressure pipes)

80100150250300350400450

0.190.220.300.400.690.840.951.17

19223141708697

119

m,,,,,,,,,,,,,,

Class NP2 (reinforced concrete, light duty, non-pressure pipes)

80100150250300350400450500600700800900

0.1960.2350.3240.5100.7360.9021.021.261.381.892.192.813.51

202433527592

104128141193223287358

,,,,,,,,,,,,,,,,,,,,,,,,,,

*Specification for concrete pipes (with and without reinforcement) ( second revision ).

( Continued )

IS : 875 (Part 1) - 1987

14



WEIGHT/MASS

mm kN kg per

(1) (2) (3) (4) (5)

Class NP2 (reinforced concrete, light duty, non-pressure pipes)

1 0001 1001 2001 4001 6001 800

4.305.156.098.189.93

12.58

438525620834

1 0131 283

m,,,,,,,,,,

Class NP3 (reinforced concrete, heavy duty, non-pressure pipes)

350400450500600700800900

1 0001 1001 200

2.352.632.913.194.024.615.927.398.13

10.3411.18

240269297325410470604754829

1 0541 140

,,,,,,,,,,,,,,,,,,,,,,

Class P1 (reinforced concrete pressure pipes safe for 20 MPa pressure tests)

80100150250300350400450500600700800900

1 0001 1001 200

0.1960.2350.3240.5100.7360.9021.021.261.381.892.192.813.514.305.156.09

202433527592

104128141193223287358437525620

,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,


80100150250300350400450500600

0.1960.2350.3240.6081.011.311.671.841.563.20

20243363

103134170188261326

,,,,,,,,,,,,,,,,,,,,


80100150250300350400

0.1960.2350.3240.7361.151.652.04

20243375

117168204

,,,,,,,,,,,,,,

Lead pipes[ see IS : 404 (Part 1)-1977* ](service and distribution pipes to be laid underground):

For working pressure 40 MPa

10152025324050

0.0180.0310.0420.0600.0740.0910.142

1.873.134.246.117.509.28

14.45

,,,,,,,,,,,,,,

*Specification for lead pipes: Part 1 For other than chemical purposes ( second revision ).

( Continued )

IS : 875 (Part 1) - 1987

15



WEIGHT/MASS

mm kN kg per

(1) (2) (3) (4) (5)


101520253240

0.0220.0380.0500.0690.1260.175

2.263.835.117.03

12.8017.82

m,,,,,,,,,,

For working pressure 100 MPa 101520

( see Note below )25

( see Note below )

0.0290.0480.067

0.105

2.964.886.86

10.75

,,,,,,

,,

Service pipes to be fixed or laid above ground:


10152025324050

0.0140.0210.0270.0360.0590.0910.142

1.452.152.743.676.009.28

14.45

,,,,,,,,,,,,,,


101520253240

0.0180.0240.0300.0690.1260.175

1.812.473.117.03

12.8017.82

,,,,,,,,,,,,

For working pressure 100 MPa 101520

( see Note below )25

( see Note below )

0.0290.0480.067

0.105

2.964.886.86

10.75

,,,,,,

,,

Cold water distribution pipes to be fixed or laid above ground:


10152025324050

0.0140.0210.0270.0360.0480.0670.084

1.452.152.743.674.856.798.53

,,,,,,,,,,,,,,


10152025324050

0.0140.0210.0270.0360.0590.0910.142

1.452.152.743.676.009.29

14.45

,,,,,,,,,,,,,,

Hot water distribution pipes to be fixed or laid above ground:


10152025324050

0.0150.0230.0310.0410.0620.0820.142

1.502.343.134.136.308.38

14.45

,,,,,,,,,,,,,,

NOTE — The maximum working pressure for these sizes is 90 MPa.

( Continued )

IS : 875 (Part 1) - 1987

16



WEIGHT/MASS

mm kN kg per

(1) (2) (3) (4) (5)


1015202532

0.0150.0270.0450.0850.132

1.502.344.568.69

13.51

m,,,,,,,,

Soil, waste, and soil and waste ventilation pipes

5075

100150

0.0500.0730.0970.160

5.077.489.88

16.36

,,,,,,,,

Flushing and warning pipes

2025324050

0.0200.0250.0320.0390.049

2.092.563.283.955.07

,,,,,,,,,,

Gas pipes:

Heavy weight gas pipes

10152025324050

0.0080.0170.0250.0340.0450.0610.071

0.811.702.603.444.576.277.20

,,,,,,,,,,,,,,

Light weight gas pipes

10152025324050

0.0080.0120.0200.0290.0370.0470.058

0.811.212.092.993.744.765.87

,,,,,,,,,,,,,,

Stoneware, salt-glazed pipes( see IS : 651-1980* )

100150200230( see Note below )250300350400450500600

0.1370.2160.3240.412

0.5100.7750.9801.261.441.772.35

14223342

5279

100128147180240

,,,,,,,,

,,,,,,,,,,,,,,

42. Plaster( see also 6 ‘Finishing’ in Table 2 )

CementLimeAcousticAnhydriteBarium sulphateFibrousGypsum

——1010101010

20.4017.250.0780.2060.2840.0880.186

2 0801 760

821299

19

m3

,,m2

,,,,,,,,

43. Sheeting

Asbestos ( see under 9 ‘Asbestos cement sheeting’ in this table )Galvanized iron ( see under 39 ‘Metal sheeting, protected’ in this table )Glass ( see under 30 ‘Glass’ in this table )Plywood 1 0.007 0.7 ,,

NOTE — This is non-preferred size and its manufacture is permitted for a limited period.

*Specification for salt-glazed stoneware pipes and fittings ( fourth revision ).

( Continued )

IS : 875 (Part 1) - 1987

17



WEIGHT/MASS

mm kN kg per

(1) (2) (3) (4) (5)

44. Slagwool — 2.65 270 m3

45. Soils and Gravels

Aluvial ground, undisturbedBroken stone ballast:

Dry, well-shakenPerfectly wet

ChalkClay:

China, compactClay fills:

Dry, lumpsDry, compactDamp, compactWet, compact

UndisturbedUndisturbed, gravellyEarth:

DryMoist

Gravel:LooseRammed

Kaolin, compactLoam:

Dry, looseDry, compactWet, compact

Loess, dryMarl, compactMud, river, wetPeat:

DrySandy, compactWet, compact

Rip-rapSand:

Dry, cleanRiverWet

Shingles:Aggregate 3 to 38 mm

Fine sand:DrySaturated

Silt, wet

—

———

—

——————

——

———

——————

————

———

—

———

15.69

15.70 to 18.3518.85 to 21.9515.70 to 18.85

21.95

10.2014.1017.2520.4018.8520.40

13.85 to 18.0515.70 to 19.60

15.7018.85 to 21.2025.50

11.7515.7018.8514.1017.25 to 18.8517.25 to 18.85

5.50 to 6.307.85

13.3512.55 to 14.10

15.10 to 15.7018.0517.25 to 19.60

13.75

15.7020.40

17.25 to 18.85

1 600

1 600 to 1 8701 920 to 2 2401 600 to 1 920

2 240

1 0401 4401 7602 0801 9202 080

1 410 to 1 8401 600 to 2 000

1 6001 920 to 2 1602 600

1 2001 6001 9201 4401 760 to 1 9201 760 to 1 920

560 to 640800

1 3601 280 to 1 440

1 540 to 1 6001 8401 760 to 2 000

1 400

1 6002 080

1 760 to 1 920

,,

,,,,,,

,,

,,,,,,,,,,,,

,,,,

,,,,,,

,,,,,,,,,,,,

,,,,,,,,

,,,,,,

,,

,,,,,,

46. Steel SectionsHot rolled [ see IS : 808 (Part 1)-1978* ]

Beams — DesignationMB 100MB 125MB 150MB 175MB 200MB 225

——————

0.1130.1310.1470.1910.2490.306

11.513.415.019.525.431.2

m,,,,,,,,,,

*Dimensions for hot-rolled steel sections: Part 1 MB series (beams) ( second revision ).

( Continued )

IS : 875 (Part 1) - 1987

18



WEIGHT/MASS

mm kN kg per(1) (2) (3) (4) (5)

Beams — DesignationMB 250MB 300MB 350MB 400MB 450MB 500MB 550MB 600

————————

0.3650.4520.5140.6040.7100.8521.001.21

37.346.152.461.672.486.9104123

m,,,,,,,,,,,,,,

Columns — Designation[ see IS : 808 (Part 2)-1978* ]

SC 100SC 120SC 140SC 160SC 180SC 200SC 220SC 250

————————

0.1960.2570.3270.4110.4950.5910.6900.839

20.026.233.341.950.560.370.485.6

,,,,,,,,,,,,,,,,

Channels — Designation[ see IS : 808 (Part 3)-1979† ]

Medium weight channel sections with sloping flanges

MC 75MC 100MC 125MC 150MC 175MC 200MC 225MC 250MC 300MC 350MC 400

———————————

0.0700.0980.1650.1920.2190.2560.3000.3560.4190.491

7.1410.016.819.622.326.130.636.342.750.1

,,,,,,,,,,,,,,,,,,,,

Medium weight channel sections with parallel flanges ( see Note below )

MCP 75MCP 100MCP 125MCP 150MCP 175MCP 200MCP 225MCP 250MCP 300MCP 350MCP 400

———————————

0.0700.0940.1280.1650.1920.2190.2560.3000.3560.4190.491

7.149.56

13.116.819.622.326.130.636.342.750.1

,,,,,,,,,,,,,,,,,,,,,,

Equal leg angles — Size[ see IS : 808 (Part 5)-1976‡ ]

ISA 2020 3.04.0

0.0090.011

0.91.1

m,,

ISA 25253.04.05.0

0.0110.0140.018

1.11.41.8

,,,,,,

ISA 30303.04.05.0

0.0140.0180.022

1.41.82.2

,,,,,,

NOTE — These sections are steel in the developmental stage and may be available subject to agreement with themanufacturer.

*Dimensions for hot-rolled steel sections: Part 2 Columns — SC series ( second revision ).†Dimensions for hot-rolled steel sections: Part 3 Channels, MC and MPC series ( second revision ).‡Dimensions for hot-rolled steel sections: Part 5 Equal leg angles ( second revision ).

( Continued )

IS : 875 (Part 1) - 1987

19



WEIGHT/MASS

mm kN kg per(1) (2) (3) (4) (5)

ISA 3535

3.04.05.06.0

0.0160.0210.0260.029

1.62.12.63.0

m,,,,,,

ISA 4050

3.04.05.06.0

0.0180.0240.0290.034

1.82.43.03.5

,,,,,,,,

ISA 4545

3.04.05.06.0

0.0210.0270.0330.039

2.12.73.44.0

,,,,,,,,

ISA 5050

3.04.05.06.0

0.0230.0290.0370.044

2.33.03.84.5

,,,,,,,,

ISA 5555

5.06.08.0

10.0

0.0400.0480.0630.077

4.14.96.47.9

,,,,,,,,

ISA 6060

5.06.08.0

10.0

0.0440.0530.0690.084

4.55.47.08.6

,,,,,,,,

ISA 6565

5.06.08.0

10.0

0.0480.0570.0760.092

4.95.87.79.4

,,,,,,,,

ISA 7070

5.06.08.0

10.0

0.0520.0620.0810.100

5.36.38.3

10.2

,,,,,,,,

ISA 7575

5.06.08.0

10.0

0.0560.0670.0870.108

5.76.88.9

11.0

,,,,,,,,

ISA 8080

6.08.0

10.012.0

0.0720.0940.1160.137

7.39.6

11.814.0

,,,,,,,,

ISA 9090

6.08.0

10.012.0

0.0800.1060.1310.155

8.210.813.415.8

,,,,,,,,

ISA 100100

6.08.0

10.012.0

0.0900.1190.1460.174

9.212.114.917.7

,,,,,,,,

ISA 110110

8.010.012.016.0

0.1310.1630.1930.252

13.416.619.725.7

,,,,,,,,

ISA 130130

8.010.012.016.0

0.1560.1930.2300.301

15.919.723.530.7

,,,,,,,,

ISA 150150

10.012.016.020.0

0.2250.2680.3510.432

22.927.335.844.1

,,,,,,,,

ISA 200200

12.016.020.025.0

0.3620.4760.5880.725

36.948.560.073.9

,,,,,,,,

( Continued )

IS : 875 (Part 1) - 1987

20



WEIGHT/MASS

mm kN kg per(1) (2) (3) (4) (5)

Unequal leg angles — Size[ see IS : 808 (Part 6)-1976* ]

ISA 30203.04.05.0

0.0110.0140.018

1.11.41.8

m,,,,

ISA 4025

3.04.05.06.0

0.0150.0190.0240.027

1.51.92.42.8

,,,,,,,,

ISA 4530

3.04.05.06.0

0.0170.0220.0270.032

1.72.22.83.3

,,,,,,,,

ISA 5030

3.04.05.06.0

0.0180.0240.0290.034

1.81.83.03.5

,,,,,,,,

ISA 60405.06.08.0

0.0360.0430.057

3.74.45.8

,,,,,,

ISA 65455.06.08.0

0.0400.0480.063

4.14.96.4

,,,,,,

ISA 7045

5.06.08.0

10.0

0.0420.0510.0660.081

4.35.26.78.3

,,,,,,,,

ISA 7550

5.06.08.0

10.0

0.0460.0550.0730.088

4.75.67.49.0

,,,,,,,,

ISA 8050

5.06.08.0

10.0

0.0480.0580.0760.092

4.95.97.79.4

,,,,,,,,

ISA 9060

6.08.0

10.012.0

0.0670.0870.1080.128

6.88.9

11.013.0

,,,,,,,,

ISA 100656.08.0

10.0

0.0740.0870.120

7.59.9

12.2

,,,,,,

ISA 10075

6.08.0

10.012.0

0.0780.1030.1270.151

8.010.513.015.4

,,,,,,,,

ISA 125716.08.0

10.0

0.0900.1190.146

9.212.114.9

,,,,,,

ISA 12595

6.08.0

10.012.0

0.0990.1310.1620.193

10.113.416.519.7

,,,,,,,,

ISA 150758.0

10.012.0

0.1340.1670.198

13.717.220.2

,,,,,,

ISA 150115

8.010.012.016.0

0.1600.1970.2350.308

16.320.124.031.4

,,,,,,,,

ISA 20010010.012.016.0

0.2250.2680.351

22.927.335.8

,,,,,,

*Dimensions of hot-rolled steel sections: Part 6 Unequal leg angles ( second revision ).

( Continued )

IS : 875 (Part 1) - 1987

21



WEIGHT/MASS

mm kN kg per

(1) (2) (3) (4) (5)

ISA 200150

10.012.016.020.0

0.2640.3150.4140.510

26.932.142.252.0

m,,,,,,

Cold formed light gauge structural steel sections ( see IS : 811-1965* ) :Light gauge sections — angles Size:

100 × 100 3.154.0

0.0470.060

4.816.07

,,,,

80 × 802.53.154.0

0.0300.0370.047

3.053.824.82

,,,,,,

60 × 60

2.02.53.154.0

0.0180.0220.0280.035

1.822.262.833.56

,,,,,,,,

50 × 50

1.62.02.53.154.0

0.0120.0150.0180.0230.029

1.211.511.872.342.93

,,,,,,,,,,

40 × 40

1.21.62.02.53.15

0.0070.0090.0120.0140.018

0.750.961.191.481.84

,,,,,,,,,,

30 × 30

1.21.62.02.5

0.0050.0070.0090.010

0.560.710.881.08

,,,,,,,,

20 × 201.21.62.0

0.0040.0050.006

0.360.460.56

,,,,,,

Channels without lips Size:

100 × 100 3.154.0

0.0700.088

7.159.01

,,,,

80 × 802.53.154.0

0.0440.0560.070

4.525.667.12

,,,,,,

60 × 60

2.02.53.154.0

0.0260.0330.0410.051

2.693.354.185.24

,,,,,,,,

50 × 50

1.62.02.53.154.0

0.0180.0220.0270.0340.042

1.792.232.763.444.30

,,,,,,,,,,

40 × 40

1.251.62.02.53.15

0.0110.0140.0170.0210.026

1.121.421.752.172.70

,,,,,,,,,,

30 × 30

1.211.62.02.5

0.0080.0100.0130.015

0.821.041.281.58

,,,,,,,,

*Specification for cold formed light gauge structural steel sections ( revised ).

( Continued )

IS : 875 (Part 1) - 1987

22



WEIGHT/MASS

mm kN kg per

(1) (2) (3) (4) (5)

Channels without lips Size:

20 × 201.251.62.0

0.0050.0070.008

0.530.660.81

m,,,,

200 × 50

2.002.503.154.00

0.0450.0560.0700.088

4.585.707.149.01

,,,,,,,,

180 × 50

2.002.503.154.00

0.0420.0520.0650.082

4.275.316.658.38

,,,,,,,,

160 × 502.002.503.15

0.0390.0480.060

3.954.926.16

,,,,,,

140 × 40

1.602.002.503.15

0.0260.0330.0410.051

2.673.334.135.17

,,,,,,,,

120 × 401.602.002.50

0.0240.0300.037

2.423.013.74

,,,,,,

100 × 40

1.251.602.002.50

0.0170.0210.0260.033

1.702.172.703.35

,,,,,,,,

80 × 30

1.251.602.002.50

0.0130.0160.0200.025

1.311.672.072.56

,,,,,,,,

60 × 301.251.602.00

0.0110.0140.017

1.121.421.75

,,,,,,

50 × 301.251.602.00

0.0100.0130.016

1.021.291.60

,,,,,,

Channels with lips Size:

100 × 100

2.002.503.154.00

0.0510.0630.0820.103

5.246.508.36

10.48

,,,,,,,,

80 × 80

1.602.002.503.15

0.0330.0410.0520.065

3.334.145.326.62

,,,,,,,,

60 × 60

1.251.602.002.50

0.0190.0240.0310.039

1.942.453.203.95

,,,,,,,,

50 × 501.251.602.00

0.0160.0200.025

1.642.082.57

,,,,,,

40 × 401.251.602.00

0.0130.0170.020

1.351.702.09

,,,,,,

30 × 30 1.251.60

0.0090.012

0.951.20

,,,,

( Continued )

IS : 875 (Part 1) - 1987

23



WEIGHT/MASS

mm kN kg per(1) (2) (3) (4) (5)

Channels with lips Size:

200 × 80

1.602.002.503.154.00

0.0470.0590.0750.0940.118

4.846.027.679.59

12.05

m,,,,,,,,

180 × 80

1.602.002.503.154.00

0.0450.0560.0710.0890.112

4.595.717.289.10

11.42

,,,,,,,,,,

160 × 80

1.602.002.503.154.00

0.0430.0530.0680.0840.106

4.345.396.898.60

10.79

,,,,,,,,,,

140 × 70

1.602.002.503.154.00

0.0380.0470.0580.0750.094

3.844.765.917.619.54

,,,,,,,,,,

120 × 60

1.251.602.002.503.15

0.0250.0310.0410.0500.063

2.523.214.145.126.38

,,,,,,,,,,

100 × 50

1.251.602.002.50

0.0210.0270.0330.043

2.132.713.354.34

,,,,,,,,

80 × 401.251.602.00

0.0170.0220.027

1.742.202.72

,,,,,,

60 × 30 1.251.60

0.0120.015

1.251.57

,,,,

50 × 30 1.251.60

0.0110.014

1.151.45

,,,,

Hat sections Size:

100 × 1002.503.154.00

0.0680.0890.115

6.899.05

11.73

,,,,,,

80 × 802.002.503.15

0.0430.0560.072

4.395.717.36

,,,,,,

60 × 601.602.002.50

0.0260.0340.043

2.633.454.34

,,,,,,

50 × 50 1.602.00

0.0220.028

2.252.88

,,,,

40 × 40 1.251.60

0.0130.018

1.361.83

,,,,

100 × 501.602.002.50

0.0340.0440.054

3.514.455.51

,,,,,,

80 × 401.251.602.00

0.0210.0280.034

2.152.833.51

,,,,,,

60 × 30 1.251.60

0.0160.020

1.642.08

,,,,

50 × 25 1.25 0.013 1.35 ,,

100 × 150 3.154.00

0.1010.134

10.2813.68

,,,,

( Continued )

IS : 875 (Part 1) - 1987

24



WEIGHT/MASS

mm kN kg per(1) (2) (3) (4) (5)

Hat sections Size:

80 × 120 3.154.00

0.0890.113

9.0811.48

m,,

60 × 902.503.154.00

0.0500.0670.084

5.126.828.59

,,,,,,

50 × 752.002.503.15

0.0330.0430.055

3.374.445.64

,,,,,,

40 × 601.602.002.50

0.0210.0280.035

2.142.823.55

,,,,,,

Rectangular box sections Size:

200 × 100 1.602.00

0.0720.090

7.359.16

,,,,

180 × 90 1.602.00

0.0650.081

6.608.22

,,,,

160 × 80 1.602.00

0.0570.071

5.857.28

,,,,

140 × 70 1.602.00

0.0500.062

5.096.34

,,,,

120 × 60 1.602.00

0.0430.053

4.345.39

,,,,

100 × 50 1.251.60

0.0280.035

2.823.58

,,,,

80 × 40 1.251.60

0.0220.028

2.232.83

,,,,

60 × 30 1.251.60

0.0160.020

1.642.08

,,,,

50 × 30 1.251.60

0.0140.018

1.441.83

,,,,

Square box section Size:

200 × 200 1.602.00

0.0970.121

9.8612.30

,,,,

180 × 180 1.602.00

0.0870.108

8.8611.04

,,,,

160 × 160 1.602.00

0.7640.096

77.859.79

,,,,

140 × 140 1.602.00

0.0670.084

6.858.53

,,,,

120 × 120 1.602.00

0.0570.071

5.857.28

,,,,

100 × 100 1.251.60

0.0370.047

3.804.84

,,,,

80 × 80 1.251.60

0.0300.038

3.013.84

,,,,

60 × 60 1.251.60

0.0220.028

2.232.83

,,,,

50 × 50 1.251.60

0.0180.023

1.842.33

,,,,

Rolled steel tee bars ( see IS : 1173-1978* )Designation

ISNT 20ISNT 30ISNT 40ISNT 50ISNT 60ISNT 80ISNT 100ISNT 150

————————

0.0090.0140.0340.0440.0530.0940.1470.223

0.91.43.54.55.49.6

15.022.8

,,,,,,,,,,,,,,,,

*Specification for hot-rolled and slit steel tee bars ( second revision ).

( Continued )

IS : 875 (Part 1) - 1987

25



WEIGHT/MASS

mm kN kg per

(1) (2) (3) (4) (5)Designation

ISHT 75ISHT 100ISHT 125ISHT 150ISST 100ISST 150ISST 200ISST 250ISLT 50ISLT 75ISLT 100ISJT 75ISJT 87.5ISJT 100ISJT 112.5

———————————————

0.1500.1960.2690.2880.0790.1540.2790.3680.0400.0700.1250.0340.0390.0490.063

15.320.027.429.4

8.115.728.437.5

4.07.1

12.73.54.05.06.4

m,,,,,,,,,,,,,,,,,,,,,,,,,,,,

Steel sheet piling sections( see IS : 2314-1963* )DesignationISPS 1 021 ZISPS 1 625 UISPS 2 222 UISPS 100 F

—————

0.4830.6410.8110.541

49.2565.3782.7055.20

,,,,,,,,

47. StoneAgateAggregateBasaltCastChalkDolomiteEmeryFlintGneissGraniteGravel:

LooseModerately rammed, dry

Green stoneGypsumLateriteLime stoneMarblePumiceQuartz rockSand stoneSlateSoap stone

——————————

————————————

25.5015.70 to 18.8527.95 to 29.0521.9521.5028.2539.2525.4023.55 to 26.4025.90 to 27.45

15.7018.8528.2521.95 to 23.5520.40 to 23.5523.55 to 25.9026.707.85 to 11.00

25.9021.95 to 23.5427.4526.45

2 6001 600 to 1 9202 850 to 2 9602 2402 1902 8804 0002 5902 400 to 2 6902 640 to 2 800

1 6001 9202 8802 240 to 2 4002 080 to 2 4002 400 to 2 6402 720

800 to 1 1202 6402 240 to 2 4002 8002 700

m3

,,,,,,,,,,,,,,,,,,

,,,,,,,,,,,,,,,,,,,,,,,,

48. Tar, CoalCrude ( see IS : 212-1983† )Naphtha, light ( see IS : 213-1968‡ )Naphtha, heavyRoad tar ( see IS : 215-1961§ )Pitch ( see IS : 216-1961|| )

—————

9.909.909.909.909.90

1 0101 0101 0101 0101 010

,,,,,,,,,,

49. Thermal InsulationUnbonded glass woolUnbonded glass rock and slag woolExpanded polystyreneCellular concrete

Grade AGrade BGrade C

Performed calcium silicate insulation (for temperature up to 650°C)

———

————

12.75 to 23.5511.30 to 19.601.45 to 2.95

Up to 29.4029.50 to 39.2039.30 to 49.0019.60 to 34.30

1 300 to 2 4001 150 to 2 000

150 to 300

Up to 3 0003 010 to 4 0004 010 to 5 0002 000 to 3 500

,,,,,,

,,,,,,,,

*Specification for steel sheet piling sections.†Specification for crude coal tar for general use ( second revision ).‡Specification for coal-based naphtha ( first revision ).§Specification for road tar ( revised ).||Specification for coal tar pitch ( revised ).

( Continued )

IS : 875 (Part 1) - 1987

26



WEIGHT/MASS

mm kN kg per

(1) (2) (3) (4) (5)50. Terra Cotta — 18.35 to 23.25 1 870 to 2 370 m3

51. TerrazzoPavingCast partitions

1040

0.240.93

2495

m2

,,

52. TilesMangalore pattern

( see IS : 654-1972* )Polystyrene wall tiles

( see IS : 3463-1966† )

—

99 × 99148.5 × 148.5

0.02 to 0.03

0.0130.013

2 to 3

1.351.35

Tile

m2

,,

53. TimberTypical Indian timbers

( see IS : 399-1963‡ )AglaiaAiniAlderAmariAmlaAmraAnjanArjunAshAxlewoodBabulBaenBaheraBakotaBalasuBallagiBanatiBenteakBerBhendiBijasalBirchBlack chuglamBlack locustBlue gumBlue pineBolaBonsumBullet woodCasuarinaCettisChampChaplashChatianChikrassyChilauniChillaChirChuglam:

BlackWhite (silver grey-wood)

CinnamonCypressDebdaruDeodarDevdamDhaman:

Grewia tiliofoliaGrewia vestita

DhupDilenia

——————————————————————————————————————

———————

————

8.345.833.636.137.854.418.337.997.068.827.707.707.994.217.55

11.134.416.626.917.557.856.137.858.348.345.056.425.208.788.346.424.855.054.076.626.427.855.64

7.856.916.425.056.285.357.06

7.707.406.426.13

850595370625800450850815720900785785815430770

1 135450675705770800625800850850515655530895850655495515415675655800575

800705655515640545720

785755655625

m3

,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,

,,,,,,,,,,,,,,

,,,,,,,,

*Specification for clay roofing tiles, Mangalore pattern ( second revision ).†Specification for polystyrene wall tiles.‡Classification of commercial timbers and their zonal distribution ( revised ).

( Continued )

IS : 875 (Part 1) - 1987

27



WEIGHT/MASS

mm kN kg per(1) (2) (3) (4) (5)

DudhiEbonyElmEucalyptusFigsFirFrashGamariGardeniaGarugaGeonGlutaGokulGrewia sp.GurjanGutelHalduHathipailaHiwarHollockHollongHoomHorse chestnutImliIndian ChestnutIndian HemlockIndian OakIndian OliveIrulJackJamanJarulJathikaiJhinganJutiliKadamKailKaimKambliKanchanKanjujKaradaKaralKaraniKararKardahiKarimgottaKasiKasumKathalKeoraKhairKhasipineKindalKokkoKongooKuchlaKumbiKurchiKurungKusumKuthanLakoochLambapattiLampatiLaurelLendiMachilus:

GambleiMacrantha

Maharukh

———————————————————————————————————————————————————————————————————

———

5.498.195.208.334.564.146.625.057.405.984.077.064.077.557.704.416.625.847.705.987.217.215.058.976.283.928.48

10.358.335.837.706.135.055.637.854.855.056.424.076.625.848.347.996.285.349.273.925.83

10.845.856.139.905.057.556.289.768.637.705.209.76

11.284.716.285.345.058.337.40

5.055.204.07

560835530850465450675515755610415720415770785450675595785610735735515915640400865

1 065850595785625515575800495515655415675595850815640545945400595

1 105595625

1 010515770640995880785530995

1 150480640545515850755

515530415

m3

,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,

,,,,,,

( Continued )

IS : 875 (Part 1) - 1987

28

TABLE 1 UNIT WEIGHT OF BUILDING MATERIALS — ContdMATERIAL NOMINAL SIZE

OR THICKNESSWEIGHT/MASS

mm kN kg per(1) (2) (3) (4) (5)

MahoganyMahuaMainaMakaiMalabar neemMangoManiawgaMapleMesuaMillaMokhaMulberryMullilamMundaniMurtengaMyrabolanNarikelNedunarOakPadaukPadriPalangPaliPapitaParrotiaPersian lilacPineyPingPinus insignisPipliPitrajPoonPoplarPulaPyinmaRajbrikhRed sandersRohiniRosewood (black wood)RudrakSalSalaiSandal woodSandanSatin woodSaykaranjiSelengSemulSilver oakSirisKala-sirisSafed-sirisSissoSpruceSujiSundriTalaumaTanakuTeakToonUdalUpasUriamVakaiVellapineWalnutWhite bombweWhite cedarWhite chuglam (silver grey-wood)White dhupYon

———————————————————————————————————————————————————————————————————————

6.628.975.643.144.416.777.405.649.769.127.996.627.216.777.709.275.495.058.487.067.065.986.283.288.485.846.138.976.135.836.776.424.413.785.988.48

10.8411.33

8.194.718.485.648.978.349.417.404.853.786.283.927.216.287.704.712.659.415.642.996.285.052.503.147.409.415.835.645.987.066.914.228.33

675915575320450690755575995930815675735690785945560515865720720610640335865595625915625595690655450385610865

1 1051 155

835480865575915850960755495385640400735640785480270960575305640515255320755960595575610720705430850

m3

,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,

NOTE — The unit of timbers correspond to average unit weight of typical Indian timbers at 12 percent moisture content.54. Water

FreshSalt

——

9.8110.05

1 0001 025

m3

,,55. Wood-Wool Building Slabs 10 0.059 6 ,,

IS : 875 (Part 1) - 1987

29

3. BUILDING PARTS AND COMPONENTS

3.1 The unit weights of building parts or components are specified in Table 2.

TABLE 2 UNIT WEIGHTS OF BUILDING PARTS OR COMPONENTS


WEIGHT/MASS

mm kN kg per

1. Ceilings

Plaster on tile or concretePlaster on wood lathSuspended metal lath and cement plaster

Suspended metal lath and gypsum plaster

1.3 cm2.5 cm2.5 cm

2.5 cm

0.250.390.74

0.49

254075

50

m2

,,,,

,,

2. Cement Concrete, Plain ( see 20 ‘Cement concentrate, plain’ in Table 1 )

3. Cement Concrete, Reinforced ( see 21 ‘Cement concrete, reinforced’ in Table 1 )

4. Damp-Proofing ( see 28 ‘Felt bituminous for waterproofing and damp proofing’ in Table 1 )

5. Earth Filling ( see 45 ‘Soils and gravels’ in Table 1 )

6. Finishing ( see also ‘Floor finishes’ given under 7 ‘Flooring’ and 8 ‘Roofing’ in Table 1 )

Aluminium foil —Plaster:

AcousticAnhydriteBarium sulphateFibrousGypsum or limeHydraulic lime or cementPlaster ceiling on wire nettingNOTE — When wood or metal lathing is used, add

10101010101010—

0.080.210.280.090.190.230.260.06

82129

9192327

6

m2

,,,,,,,,,,,,,,

7. Flooring

Asphalt flooringNOTE — For macadam finish, addCompressed cork

Floors, structural:Hollow clay blocks including reinforcement and mortar jointing between blocks, but excluding any concrete topping

101010

100125150175200

0.220.260.04

1.471.671.862.162.55

2227

4

150170190220260

,,,,,,

,,,,,,,,,,

NOTE — Add extra for concrete toppingHollow clay blocks including reinforcement and concrete ribs between blocks, but excluding any concrete topping

100115125140150175200

1.181.271.371.471.571.761.96

120130140150160180200

,,,,,,,,,,,,,,

NOTE — Add extra for concrete topping.

( Continued )

Negligible

IS : 875 (Part 1) - 1987

30

TABLE 2 UNIT WEIGHTS OF BUILDING PARTS OR COMPONENTS — Contd


WEIGHT/MASS

mm kN kg perHollow concrete units including any concrete topping necessary for constructional purposes

100125150175200230

1.671.962.162.352.653.14

170200220240270320

m2

,,,,,,,,,,

Floors, wood:

Hard wood 2228

0.160.20

1620.5

,,,,

Soft woodWeight of mastic used in laying wood

block flooring

2228—

0.110.130.015

1113.51.5

,,,,,,

NOTE — All thicknesses are ‘finished thicknesses’.Floor finishes:

Clay floor tiles ( see IS : 1478-1969* )

NOTE — This weight is ‘as laid’ butexcludes screeding.

12.5 to 25.4

0.10 to 0.2 10 to 20 ,,

Magnesium oxychloride:Normal type (saw dust filler)Heavy duty type (mineral filler)

Parquet flooringRubber ( see IS : 809-1970† )

Terra cotta, filled ‘as laid’Terrazzo paving ‘as laid’

1010—3.24.86.4

—10

0.1420.2160.08 to 0.120.048 to 0.0620.070 to 0.090.093 to 0.1305.54 to 7.060.23

14.5228 to 124.9 to 6.37.1 to 9.59.5 to 13.2

570 to 72024

,,,,,,,,,,,,

m3

m2

8. Roofing

Asbestos cement sheeting( see ‘Asbestos cement sheeting’ in Table 1 ).

Allahabad tiles (single) including battens ( see Note below )

Allahabad tiles (double) including battens ( see Note below )

Country tiles (single) with battens ( see Note below )

Country tiles (double) with battens ( see Note below )

Mangalore tiles with battens ( see Note below )

Mangalore tiles bedded in mortar over flat tiles ( see Note below )

Mangalore tiles with flat tiles ( see Note below )

—

—

—

—

—

—

—

0.83

1.67

0.69

1.18

0.64

1.08

0.78

85

170

70

120

65

110

80

,,

,,

,,

,,

,,

,,

,,

Copper sheet roofing including laps and rolls

Flat Roofs:Clay tiles hollow ( see 7 ‘Flooring’ in

this table )Concrete hollow precast ( see 7

‘Flooring’ in this table )Galvanized iron sheeting ( see 39

‘Metal sheeting, protected’ in Table 1 )

Glazed Roofing:Glazing with aluminium alloy bars for

spans up to 3 mGlazing with lead-covered steel bars

at 0.6 m centresStates on battensThatch with battens

0.560.72

6.4

6.4

——

0.080.10

0.19

0.25 to 0.28

0.34 to 0.490.34 to 0.49

810

19.5

26 to 29

35 to 5035 to 50

,,,,

,,

,,

,,,,

NOTE — Weights acting vertically on horizontal projection to be multiplied by cosine of roof angle to obtain weightsnormal to the roof surface.

*Specification for clay flooring tiles ( first revision ).†Specification for rubber flooring materials for general purposes ( first revision ).

( Continued )

IS : 875 (Part 1) - 1987

31

4. STORE AND MISCELLANEOUS MATERIALS

4.1 Units weights of store and miscellaneous

materials intended for dead load calculationsand other general purposes are given inAppendix A.

TABLE 2 UNIT WEIGHTS OF BUILDING PARTS OR COMPONENTS — Contd


WEIGHT/MASS

mm kN kg per

Roof finishes:Bitumen mecadamFelt roofing ( see 28 ‘Felt, bituminous

for water-proofing and damp-proofing’ in Table 1 )

Glass silk, quiltedLead sheetMortar screeding

1010

0.50.8

10

0.220.008

0.050.070.21

220.8

57

21

m2

,,

,,,,,,

9. Walling (IS : 6072-1971*)

Autoclaved reinforced cellular concrete wall slabsClass AClass BClass CClass DClass E

Brick masonry ( see 36 ‘Masonry, brick’ in Table 1 )

Concrete blocks ( see 11 ‘Block’ in Table 1 )

Stone masonry ( see 37 ‘Masonry, stone’ in Table 1 )

—————

8.35 to 9.807.35 to 8.356.35 to 7.355.40 to 6.354.40 to 5.40

850 to 1 000750 to 850650 to 750550 to 650450 to 550

m3

,,,,,,,,

Partitions:Brick wallCinder concreteGalvanized iron sheetHollow glass block (bricks)

Hollow blocks per 200 mm of thickness:Ballast or stone concreteClayClinker concreteCoke breeze concreteDiatomaceous earthGypsumPumice concreteSlag concrete, air-cooledSlag concrete, foamed

Lath and plasterSolid blocks per 20 mm of thickness:

Ballast or stoneClinker concreteCoke breeze concretePumice concreteSlag concrete, foamed

Terrazzo cast partitionsTimber studding plastered

10075—

100

202020202020202020—

202020202040—

1.911.130.150.88

0.2010.2010.2209.1760.0930.1370.1770.1960.1860.392

0.4510.3000.2210.2210.2500.9329.981

195115

1590

20.520.522.518

9.51418201940

4630.522.522.525.595

100

m2

,,,,,,

,,,,,,,,,,,,,,,,,,,,

,,,,,,,,,,,,,,

NOTE — For unit weight of fixtures and fittings required to buildings including builder’s hardware, reference may bemade to appropriate Indian Standards.

*Specification for autoclaved reinforced cellular concrete wall slabs.

IS : 875 (Part 1) - 1987

32

A P P E N D I X A[ Clauses 1.1.1 ( Note ) and 4.1 ]

UNIT WEIGHTS OF STORE AND MISCELLANEOUS MATERIALS

MATERIAL WEIGHT/MASS ANGLE OF FRICTION, DEGREESkN/m3 kg/m3

1. Agricultural and Food Products

ButterCoffee in bagsDrinks in bottles, in boxesEggs, packedEats, oilFish meal

Flour in sacks up to 1 m heightForage (bales)Fruits

8.455.507.352.955.804.902.20 to 5.901.253.45

860560750300590500225 to 600125350

—————45———

Grains:

BarleyCorn, shelledFlax seedOatsRiceSoyabeansWheatWheat flour

Grain sheaves up to 4 m stack heightGrain sheaves over 4 m stack heightGrass and clover

6.757.557.355.306.557.358.156.850.981.453.45

690770750540670750830700100150350

27273030333028303030—

Hay:

CompressedLoose up to about 3 m stack height

Honey

1.650.69

14.10

17070

1 440

———

Hops:

In sacksIn cylindrical hop binsSewn up or compressed in cylindrical shape in

hop cloth

1.654.602.85

170470290

———

Malt:

CrushedGerminated

Meat and meat productsMilkMolassesOnion in bagsOil cakes, crushedPotatoesPreserves (tins in cases)

3.901.857.05

10.054.405.405.807.054.90 to 7.85

400190720

1 025450550590720500 to 800

20————00

30—

Salt:

BagsBulk

7.059.40

720960

—30

Seeds:

HeapsSacks

4.90 to 7.853.90 to 6.85

500 to 800400 to 700

25—

Straw and chaff:

Loose up to about 3 m stack heightCompressed

0.451.65

45170

——

Sugar:

CrystalCube sugar in boxes

Sugar beet, pressed outTobacco bundlesVinegar

7.357.857.853.45

10.40

750800800350

1 080

30————

IS : 875 (Part 1) - 1987

33


2. Chemicals and Allied Materials

Acid, hydrochloricAcid, nitric 91%Acid, sulphuric 87%AlcoholAlum, pearl, in barrelAmmonia, liquidAmmonium chloride, crystallineAmmonium nitrateAmmonium sulphateBeeswaxBenzoleBenzene hexachlorideBicarbonate of sodaBoneBoraxCalciteCamphorCarbon disulphideCaseinCaustic sodaCreosoleDicalcium phosphateDisodium phosphateIodineOils in bottles or barrels

11.7514.8017.557.655.208.858.157.05 to 9.807.05 to 9.009.408.908.756.40

18.6517.1526.509.70

12.7513.2513.8510.506.653.90 to 4.80

48.555.70 to 8.90

1 2001 5101 790

780530900830720 to 1 000720 to 920960910890650

1 9001 7502 700

9901 3001 3501 4101 070

6.80400 to 490

4 950580 to 910

——————

30-4025

32-45——4530————————45

30-45——

Oil, linseed:

In barrelsIn drums

Oil, turpentinePaintsParaffin waxPetroleumPhosphorus

5.707.058.509.407.85 to 9.409.90

17.85

580720865960800 to 960

1 0101 820

———————

Plastics:

Cellulose acetateCellulose nitrateMethyl methacrylatePhenol formaldehydePolystryrenePolyvinyl chloride (Perspex)Resin bonded sheetUrea formaldehyde

PotashPotassiumPotassium nitrateRed lead, dryRed lead, pasteRosin in barrels

12.25 to 13.3513.25 to 15.7011.6012.5510.4011.75 to 13.2512.85 to 13.5513.25 to 13.5514.408.659.90

20.7087.306.75

1 250 to 1 3601 350 to 1 6001 1851 2801 0601 200 to 1 3501 310 to 1 3801 350 to 1 3801 470

8801 0102 1108 900

690

——————————————

Rubber:

RawVulcanized

SaltpetreSodium silicate in barrelsSulphurTalcVarnishesVitriol, blue, in barrels

8.90 to 9.408.90 to 9.109.918.35

20.1027.459.407.05

910 to 960910 to 930

1 010850

2 0502 800

960720

————————

3. Fuels

Brown coalBrown coal briquettes heaped

6.857.85

700800

—35

IS : 875 (Part 1) - 1987

34


Brown coal briquettes, stackedCharcoal

12.752.95

1 300300

——

Coal:

Untreated, mine-moistIn washeriesDustAll other sorts

9.8011.756.858.35

1 0001 200

700850

350

2535

Coke:

Furnace or gasBrown coal, low-temperatureHard, raw coalHard, raw coal, mine-damp

Diesel oilFirewood, choppedPetrolWood in chipsWood shavings, looseWood shavings, shaken down

4.909.808.359.809.403.906.751.951.452.45

5001 000

8501 000

960400690200150250

35353535

045

0453535

4. Manures

Animal manures:Loosely heapedStacked dung, up to about 2.5 m stack heightArtificial manures

11.7517.6511.75

1 2001 8001 200

4545

24.30

5. Metals and Alloys

AluminiumCastWroughtSheet per mm of thickness per m2

25.30 to 26.6025.90 to 27.450.028

2 580 to 2 7102 640 to 2 800

2.8

———

Antimony, pure:

AmorphousSolid

60.9065.70

6 2106 700

——

Bismuth:

LiquidSolid

98.0795.02 to 97.09

10 0009 690 to 9 900

——

Cadmium:

CastWroughtCalciumChromium

83.75 to 84.0585.0315.6063.95 to 66.00

8 540 to 8 5708 6701 5906 520 to 6 730

————

Cobalt:

CastWrought

83.25 to 85.1088.45

8 490 to 8 6809 020

——

Copper:

CastWroughtSheet per mm of thickness

86.20 to 87.6586.70 to 87.650.09

8 790 to 8 9408 840 to 8 940

8.7

———

Gold:

CastWrought

188.75 to 189.55189.55

19 250 to 19 33019 330

——

Iron:

PigGrey, castWhite, castWrought

70.6068.95 to 69.9074.35 to 75.7075.50

7 2007 030 to 7 1307 580 to 7 7207 700

————

IS : 875 (Part 1) - 1987

35


Lead:

CastLiquidWroughtSheet per mm of thickness

MagnesiumManganeseMercuryNickelPlatinum

111.20105.00111.40

0.1116.45 to 17.1572.55

133.3581.20 to 87.20

210.25

11 34010 71011 360

111 680 to 1 7507 400

13 6008 280 to 8 890

21 440

—————————

Silver:

CastLiquidWrought

102.0 to 102.8593.15

103.35 to 103.55

10 400 to 10 4909 500

10 540 to 10 560

———

Sodium:

LiquidSolid

9.109.30

930950

——

TungstenUranium

188.30180.45

19 20018 400

——

Zinc:

CastWroughtSheet per mm of thickness

68.95 to 70.2070.500.07

7 030 to 7 1607 190

7

———

Alloys:

Aluminium and copperAluminium 10%, copper 90%Aluminium 5%, copper 95%Aluminium 3%, copper 97%Aluminium 91%, zinc 9%Babbit metal (tin 90%, lead 5%, copper 5%)Wood’s metal (bismuth 50%, lead 25%,

cadmium 12.5%, tin 12.5%)

75.4082.0085.1027.4571.7095.00

7 6908 3608 6802 8007 3109 690

——————

Brasses:

Muntz metal (copper 60%, zinc 40%)Red (copper 90%, zinc 10%)White (copper 50%, zinc 50%)

80.6084.2580.30

8 2208 5908 190

———

Yellow (copper 70%, zinc 30%):

CastDrawnRolled

82.7585.1083.85

8 4408 6808 550

———

Bronzes:

Bell metal (copper 80%, tin 20%)Gun metal (copper 90%, tin 10%)Cadmium and tin

85.6086.1075.40

8 7308 7807 690

———

German Silver:

Copper 52%, zinc 26%, nickel 22%Copper 59%, zinc 30%, nickel 11%Copper 63%, zinc 30%, nickel 7%

82.7581.7081.40

8 4408 3308 300

———

Gold and Copper:

Gold 98%, copper 2%Gold 90%, copper 10%

184.75168.20

18 84017 150

——

IS : 875 (Part 1) - 1987

36


Lead and Tin:

Lead 87.5%, tin 12.5%Lead 30.5%, tin 69.5%

Monel metal, cast (nickel 70%, copper 30%)

103.8581.1087.00

10 5908 2708 870

———

Steel:

CastWrought mildBlack plate per mm of thickness

77.0076.800.08

7 8507 830

8

———

Steel sections ( see 46 ‘Steel sections’ in Table 1 )

6. Miscellaneous Materials

Aggregate, coarseAshes, coal, dry, 12 mm and underAshes, coal, dry, 75 mm and underAshes, coal, wet, 12 mm and underAshes, coal, wet, 75 mm and underAsphalt, crushed, 12 mm and underAmmonium nitrate, prillsBoneBooks and files, stackedCalcium ammonium nitrateCopper sulphate, groundChalkChinaware, earthenware, stacked (including cavities)Clinker, furnace, cleanDiammonium phosphateDouble salt (ammonium sulphate nitrate)Filling cabinets and cupboards with contents, in

records offices, libraries, archivesFlue dust, boiler house, dryFly ash, pulverised

10.80 to 15.705.50 to 6.305.50 to 6.307.05 to 7.857.05 to 7.857.053.55 to 8.35

18.658.359.80

11.7521.9510.807.857.85 to 8.507.05 to 9.305.90

5.50 to 7.055.50 to 7.05

1 100 to 1 600560 to 645560 to 645720 to 800720 to 800720360 to 850

1 900851

1 0001 2002 2401 100

800800 to 865720 to 950600

560 to 720560 to 720

304038525030-4527——2830——302934—

≥ 30—

Glass:

Glass, solidWoolIn sheets

GlueGypsum, calcined, 12 mm and underGypsum, calcined, powderedGypsum, raw, 25 mm and underHides

23.50 to 26.700.16 to 1.18

25.5012.558.60 to 9.409.40 to 12.55

14.10 to 15.70

2 400 to 2 72016 to 120

2 6001 280

889 to 960960 to 1 280

1 440 to 1 600

————4045

30-45

DrySalted 8.65 880 —

IceLeather put in rowsLime, ground, 3 mm and underLime, hydrated, 3 mm and underLime, hydrated, pulverizedLime pebbleLimestone, agricultural, 3 mm and underLimestone, crushedLimestone dustMagnesite, caustic, in powder formMagnesite, sinter and magnesite, granularPhosphate, rock, pulverizedPhosphate rockPhosphate sandPotassium carbonatePotassium chloride, pelletsPotassium nitratePotassium sulphatePyrites, pellets

8.907.859.406.305.00 to 6.308.25 to 8.75

10.6013.30 to 14.108.65 to 14.907.85

19.609.40

11.75 to 13.3514.10 to 15.707.95

18.85 to 20.404.856.55 to 7.45

18.85 to 20.40

910800960640510 to 640840 to 890

1 0801 355 to 1 440

880 to 1 520800

2 000960

1 200 to 1 3601 440 to 1 600

8101 920 to 2 080

495670 to 760

1 920 to 2 080

——

≥ 4530-4530-45

≥ 4530-4530-4538-45

——

40-5230-4530-4530-4530-45

≥ 3045

30-45

Only green

IS : 875 (Part 1) - 1987

37


PumiceRubbish:

5.80 to 9.90 590 to 1 010 —

BuildingGeneral

Salt, common, dry, coarseSalt, common, dry, fineSalt cake, dry, coarseSalt cake, dry, pulverizedSand, bank, dampSand, bank, drySand, silica, drySaw dust, looseSilica gelSoda ash, heavySoda ash, lightSodium nitrate, granularSulphur, crushed, 12 mm and underSulphur, 76 mm and underSulphur, powderedSingle superphosphate (S.S.P.), granulatedSlag, furnace, crushed

13.806.306.30 to 10.00

11.00 to 12.5513.3511.20 to 13.3517.25 to 20.4014.10 to 17.2514.10 to 15.701.574.408.65 to 10.204.70 to 6.00

11.00 to 12.557.85 to 8.258.65 to 13.357.85 to 9.407.65 to 8.25

14.90

1 410645640 to 1 020

1 120 to 1 2801 3601 140 to 1 3601 760 to 2 0801 440 to 1 7601 440 to 1 600

160450880 to 1 040480 to 610

1 120 to 1 280800 to 840880 to 1 360800 to 960780 to 840

1 520

——

30-4530-45

30354530

30-3530

30-45353724

35-4532

30-453735

Steel goods:

Cylinders, usually stored for carbonic acid, etcSheets, railway rails, etc, usually stored

Trisodium phosphateTriple superphosphateTurfUrea, prills

13.8044.009.407.85 to 8.652.85 to 5.706.40

1 4104 490

960800 to 880

2 910 to 5 810650

——

30-4530-45

—23-26

7. Ores

AntimonyFerrous sulphideFerrous sulphide ore

waste after roastingIron ore, compact storingMagnesium ore

29.8026.5013.85

29.8019.60

3 0402 7001 400

3 0402 000

———

——

8. Textiles, Paper and Allied Materials

Cellulose in bundlesCotton, compressedFlax, piled and compressed in balesFursJute in bundles

7.3512.752.958.906.85

7501 300

300910700

—————

Paper:

In bundles and rollsNewspapers in bundlesPut in rows

Thread in bundlesWood, compressed

6.853.90

10.804.90

12.75

700400

1 100500

1 300

—————

Bureau of Indian Standards

BIS is a statutory institution established under the Bureau of Indian Standards Act, 1986 to promoteharmonious development of the activities of standardization, marking and quality certification of goods andattending to connected matters in the country.

Copyright

BIS has the copyright of all its publications. No part of these publications may be reproduced in any formwithout the prior permission in writing of BIS. This does not preclude the free use, in the course ofimplementing the standard, of necessary details, such as symbols and sizes, type or grade designations.Enquiries relating to copyright be addressed to the Director (Publications), BIS.

Review of Indian Standards

Amendments are issued to standards as the need arises on the basis of comments. Standards are alsoreviewed periodically; a standard along with amendments is reaffirmed when such review indicates that nochanges are needed; if the review indicates that changes are needed, it is taken up for revision. Users ofIndian Standards should ascertain that they are in possession of the latest amendments or edition byreferring to the latest issue of ‘BIS Catalogue’ and ‘Standards : Monthly Additions’.

This Indian Standard has been developed by Technical Committee : CED 37

Amendments Issued Since Publication

Amend No. Date of Issue

Amd. No. 1 December 1997

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Indian Standard

IS : 875 ( Part 2 ) - 1987(Reaffirmed 1997)

CODE OF PRACTICE FORDESIGN LOADS (OTHER THAN EARTHQUAKE)

FOR BUILDINGS AND STRUCTURESPART 2 IMPOSED LOADS

(Second Revision)~-

Sixtll Reprint JUNE 1998

UDC 624~042.3 : 006.76

@ Copyright 1989


NEW DELHI 110002

Gr 8 March 1989

IS : 875 ( Part 2 ) - 1987

.I Indian Standard

CODEOFPRACTICEFORDESIGNLOADS(OTHERTHANEARTHQUAKE)

FORBUILDINGSANDSTRUCTURESPART 2 IMPOSED LOADS

(Second Rev’sion)

Structural Safety Sectional Committee, BDC 37

Chairman

BRIG L. V. R A M A K R I S H N A

MembersD R K. G. BHATIA

S HRI M. S. BHATIA

SHRT N. K. BHATTACHARYA

SHRI S. K. MALHOTRA (Alternate )D R S. C. C HAKRABARTI

SHKI A. DA T T A ( AIIernare )CHIEF ENGINEER ( NDZ ) II

SUPERINTENDING SURVEYOR OF W O R K S

( NDZ ) II ( Alternate )D R P. DA Y A R A T N A M

D R A. S. R. SAI ( Alternate )D E P U T Y M UNICIPAL COMMISSIOKER ( ENGG )

C ITY ENGINEER ( Alternate )D IRECTOR ( CMDD-I )

D EPUTY D IRECTOR ( CMDD-I ) ( Alternate )M A J- GEN A. M. GOGLEKAR

P ROF D. N. TRIKHA ( Alternate )SHRI A. C. GUPTASHRI P. SEN G U P T A

SHRI M. M. GHOSH ( Alternate )SHRI G. B. JA H A G I R D A R

JOINT D IRECTOR STANDARDS ( B & S ), CBSHRI S. P. JOSHI

SHRI A. P. MULL ( Alternate )S HRI S. R. KUI.KARNI

SHRI S. N. PAL ( Alternate )S HRI H. N. MI S H R A

SHRI R. K. PUNHANI ( Alternate )S HRI T. K. D. MU N S H I

D R 6. RA J K U M A R

D R M. N. KESHWA RA O

S HRI S. GO M A T H I N A Y A G A M ( Alternate )D R T. N. SUBBA R A O

DR S. V. LO N K A R ( AIfernafe )S HRI P. K. RA Y

SHRI P. K. MUKHERJEE ( Alternate )SHRI S. SE E T H A R A M A N

SHRI S. P. C HAKRABORTY ( Alternate )

RepresentingEngineer-in-Chief’s Branch, Army Headquarters, New

Delhi

Bharat Heavy Electricals Ltd ( Corporate, Research &Development Division ), Hyderabad

In pe;rs;;l) capacity ( A-2136, Sa/darjmg Enclave, New

Engineer-in-Chief’s Branch, Army Headquarters, NewDe Ihi

Central Building Research Institute ( CSIR ), Roorkee

Central Public Works Department, New Delhi

Indian Institute of Technology, Kanpur

Municipal Corporation of Greater Bombay, Bombay

Central Water Commission, New Delhi

Institution of Engineers ( India ), Calcutta

National Thermal Power Corporation Ltd, New DelhiStewarts and Lloyds of India Ltd, Calcutta

National Industrial Development Corporation Ltd, NewDelhi

Ministry of RailwaysTata Consulting Engineers, New Delhi

M. N. Dastur & Co, Calcutta

Forest Research institute and Colleges, Dehra Dun

Engineers India Ltd. New DelhiNational Council for Cement and Building Materials,

New DelhiStructural Engineering Research Centre ( CSIR ), Madras

Gammon India Ltd, Bombay

Indian Engineering Association, Calcutta

Ministry of Surface Transport ( Roads Wing ), New Delhi

( Continued on page 2 )

0 Copyright 1989BUREAU OF INDIAN STANDARDS

This publication is protected under the Indian Cop.vright Act ( XIV of 1957) and reproduction in whole orin part by any means except with written permission of the publisher shall be deemed to be an infringement

of copyright under the said Act.

IS : 875 ( Part 2 ) - 1987

( Continuedfrom page 1 )

MembersSHRI M. C. SHARMASHRI K. S. SRINIVASAN

SHRI A. K. LAL ( Alternate )SHRI SUSHJL KLIMAR

SHRI G. RAMAN,Director ( Civ Engg )

RepresentingIndia Meteorological Department, New DelhiNational Buildings Organization, New Delhi

National Building Construction Corporation, Limited,New Delhi

Director General, BIS ( Ex-officio Member )

Secretary

SHRI B. R. NARAYANAPPADeputy Director ( Civ Engg ), BIS

Panel on Loads ( Other than Wind Loads ), BDC 37 : P3

ConvenerD R T. N. SUBBA RA O

DR S. V. LONKAR ( Alternate )

MembersDR T. V. S. R. APPA RA O

DR M. N. KESHAVA RAO ( Alternate )SHRI S. R. KULKARNISHRI M. L. MLHTA

SHRI S. K. DATTA ( Alternate )D R C. N. SRINIVASANSUPERINTENDING ENGINEER ( D )

EXECUTIVE ENGINEER ( D ) VII ( Alternate )D R H. C. V ISVESVARAYA

Gammon India Limited, Bombay

Structural Engineering Research Centre, CSIR Campus,Madras

M. N. Dastur & Co Ltd, CalcuttaMetallurgical & Engineering Consultants ( India ) Ltd.

Ranchi

M/s C. R. Narayana Rao, MadrasCentral Public Works Department ( Central Designs

Organization ), New Delhi

National Council for Cement and Building Materials,New Delhi

IS : 875 ( Part 2 ) - 1987

C O N T E N T S

0.

1.

2.

3.

FOREWORD . . . *.. . . .

SCOPE . . . . . . . . .

TERMINOLOGY . . . . . . . . .

IMPOSED LOADS ON FLOORS DUE TO USE AND OCCUPANCY

3.1 Imposed Loads . . .

3.1.1 Load Application . . .

3.1.2 Loads Due to Partitions . . .

3.2

3.3

4.

4.1

4.2

4.3

4.4

4.5

5.

6.

6.1

6.2

6.3

6.4

7.

Reduction in Imposed Loads on Floors

Posting of Floor Capacities . . .

IMPOSED LOADS ON ROOFS . . .

Imposed Loads on Various Types of Roofs

Concentrated Load on Roof Coverings

Loads Due to Rain . . .

Dust Load . . .

Loads on Members Supporting Roof Coverings

. . .

. . .

. . .

. . .

. . .

. . .

. . .

. . .

. . .

. . .

IMPOSED HORIZONTAL LOADS ON PARAPETS AND BALUSTRADES

LOADING EFFECTS DUE TO IMPACT AND VIBRATION

Impact Allowance for Lifts, Hoists and Machinery

Concentrated Imposed Loads with Impact and Vibration

Impact Allowances for Crane Girders . . .

Crane Load Combinations . . . . . .

OTHER LOADS . . . . . . . . .

. . .

. . .

. . .

. . .

. . .

. . .

. . .

. . .

. . .

. . .

. . .

. . .

. . .

. . .

. . .

. . .

. . .

. . .

.,*

. . .

. . .

f..

APPENDIX A ILLUSTRATIVE EXAMPLE SHOWING REDUCTION OF UNIFORMLY DISTRIBUTEDIMPOSED FLOOR LOADS IN M U L T I-STOREYED B UILDINGS FOR D ESIGN OF

COLUMNS

. . .

. . .

. . .

. . .

. . .

..,

. . .

. . .

. . .

.,.

. . .

. . .

. . .

. . .

.,.

. . .

. . .

.I

. . .

. . .

. . .

. . .

Page

4

5

5

6

6

12

12

12

13

13

13

13

13

13

13

13

14

14

15

15

16

16

17

IS : 875 ( Part 2 ) - 1987

Indian Standard

CODE OF PRACTICEDESIGN LOADS (OTHER THAN

FOREARTHQUAKE)

FOR BUILDINGS AND STtiUCTURESPART 2 IMPOSED LOADS

(Second Revision)

0 . F O R

0.1 This Indian Standard ( Part 2 ) ( SecondRevision ) was adopted by the Bureau of IndianStandards on 31 August 1987. after the draftfinalized by the Structural Safety Sectional Com-mittee had been approved by the Buildmg Divi-sion Council.0.2 A building has to perform many functionssatisfactorily. Amongst these functions are theutility of the building for the intended useand occupancy, structural safety, fire safety;and compliance with hygienic, sanitation, venti-lation and day light standards. The design ofthe building is dependent upon the minimumrequirements prescribed for each of the abovefunctions. The minimum requirements pertainingto the structural safety of buildings are beingcovered in this Code by way of laying downminimum design loads which have to be assumedfor dead loads, imposed loads, snow loads andother external loads, the structure would berequired to bear. Strict conformity to loadingstandards recommended in this Code, it is hoped,will not only ensure the structural safety of thebuildings which are being designed and construct-ed in the country and thereby reduce the hazardsto life and property caused by unsafe structures,but also eliminate the wastage caused by assumingunnecessarily heavy loadings.

0.3 This Code was first published in 1957 for theguidance of civil engineers, designers and archi-tects associated with the planning and design ofbuildings. It included the provisions for the basicdesign loads ( dead loads, live loads, wind loadsand seismic loads ) to be assumed in the designof buildings. In its firs! revision in 1964, thewind pressure provisions were modified on thebasis of studies of wind phenomenon and itseffects on structures, undertaken by the specialcommittee in consultation with the IndianMeteorological Department. In addition to this,new clauses on wind loads for butterfly typestructures were included; wind ,pressure coeffi-cients for sheeted roofs, both curved and sloping,were modified; seismic load provisions were delet-ed ( separate code having been prepared ) andmetric system of weights and measurements wasadopted.

E W O R D

0.3.1 With the increased adoption of the Code,a number of comments were received on the pro-visions on live load values adopted for differentoccupancies. Simultaneously live load surveyshave been carried out in America and Canada toarrive at realistic live loads based on actual deter-mination of loading ( movable and immovable )in different occupancies. Keeping this in viewand other developments in the field of windengineering, the Sectional Committee responsiblefor the preparation of the Code has decided toprepare the second revision of IS : 875 in thefollowing five parts :

Part 1 Dead loadsPart 2 Imposed loadsPart 3 Wind loadsPart 4 Snow loadsPart 5 Special loads and load combinationsEarthquake load is covered in a separate

standard, namely IS : 1893-1984* which shouldbe considered along with above loads.

0.3.2 This Code ( Part 2 ) deals with imposedloads on buildings produced by the intendedoccupancy or use. In this revision, the followingimportalit changes have been made:

a) The use of the term ‘live load’ has beenmodified to ‘imposed load’ to cover notonly the physical contribution due topersons but also due to nature of occu-pancy, the furniture and other equipmentswhich are a part of the character of theoccupancy.

b) The imposed loads on floors and roofshave been rationalized based on thecodified data available in large numberof latest foreign national standards, andother literature. Further, these valueshave been spelt out for the major occu-pancies as classified in the NationalBuilding Code of India as well as thevarious service areas appended to the majoroccupancies.

*Criteria for earthquake resistant design of structures(fourth revision ).

4

C)

4

e)

f >

g>

The reduction of imposed loads fordesign of vertical supporting membersin multi-storeyed b u i l d i n g s h a s b e e nfurther increased from 40 to 50 percent.Provision has been included for signposting of loads on floors in view ofthe different loadings specified. fordifferent occupancies and to avoid possi-ble misuse in view of conversion ofoccupancies.The value of loads on parapets andbalustrades have been revised with itseffect taken both in the horizontal andvertical directions.In the design of dwelling units plannedand executed in accordance withIS : 8888-1979*, an imposed load of 1.5kN/m* is allowed.SI Units have been used in the Code.

0.3.3 The buildings and structural systems shallprovide such structural integrity that the hazardsassociated with progressive collapse such as thatdue to local failure caused by severe overloads orabnormal loads not specifically covered thereinare reduced to a level consistent with goodengineering practice.

0.3.4 Whenever buildings are designed for futureadditions of floor at a later date, the number ofstoreys for which columns/walls, foundations, etc,have been structurally designed may be posted ina conspicuous place similar to posting of floorcapacities and both could be placed together.0.4 The Sectional Committee responsible for thepreparation of this Code has taken into account- -

*Guide for requirements of low income housing.

IS : 875 ( Part 2 ) - 1987

the prevailing practices in regard to loadingstandards followed in this country by the variousmunicipal authorities and has also taken note ofthe developments in a number of countries abroad.In the preparation of this Code, the followingnational standards have been examined :

a) BS 6399 : Part 1 : 1984 Design Loading forBuildings Part I: Code of Practice forDead and Imposed Loads. British Stand-ards Institution.

b) AS : 1170, Part 1-1983 - SAA LoadingCode, Part I Dead and Live Loads.Australian Standards Institution.

c) NZS 4203-1976 New Zealand StandardGeneral Structural Design and DesignLoading for Building. Standards Associa-tion of New Zealand.

d) ANSI. A 58.1 - 1982American StandardBuilding Code Requirements for MinimumDesign Loads in Buildings and OtherStructures.

e)

f )

!?I

h)

National Building Code of Canada ( 1977 )Supplement No. 4. Canadian StructuralDesign Manual.

DIN 1055 Sheet 3 - 1971 Design Loadsfor Buildings - Live Load ( West GermanLoading Standards ).

IS0 2103-1986 Loads due to use andoccupancy in residential and public build-ings.

IS0 2633-1974 Determination of Impos-ed Floor Loads in Production Buildingsand Warehouses. lnternational Organiza-tion for Standardization.

1. SCOPE

1.1 This standard ( Part 2) covers imposed loads*( live loads ) to be assumed in the design of build-ings. The imposed !oads, specified herein, areminimum loads which should be taken into con-sideration for the purpose of structural safety ofbuildings.

1.2 This Code does not cover detailed provisionsfor loads incidental to construction and specialcases of vibration, such as moving machinery,heavy acceleration from cranes, hoists and thelike. Such loads shall be dealt with individuallyin each case.

2. TERMINOLOGY

2.0 For the purpose of this Code, the followingdefinitions shall apply.

*The word ‘imposed load’ is used through out insteadof ‘live load’ which is synonymous.

2.1 Imposed Load - The load assumed to beproduced by the intended use or occupancy of abuilding, mcluding the weight of movable parti-tions, distributed, concentrated loads, load dueto impact and vibration, and dust load but ex-cluding wind, seismic, snow and other loads dueto temperature changes, creep, shrinkage, differ-ential settlement, etc.2.2 Occupancy or Use Group - The principaloccupancy for which a building or part of a build-ing is used or intended to be used; for the pur-pose of classification of a building according tooccupancy, an occupancy shall be deemed toinclude subsidiary occupancies which are contin-gent upon it. The occupancy classification isgiven from 2.2.1 to 2.2.8.

2.2.1 Assembly Buildings - These shall includeany building or part of a building where groupsof people congregate or gather for amusement,recreation, social, religious, patriotic, Civil, traveland similar purposes, for example, theatres,motion picture houses, assembly halls, city halls,

5

IS : 875 ( Part 2 ) - 1987

marriage halls, town halls, auditoria, exhibitionhalls, museums, skating rinks, gymnasiums,restaurants ( also used as assembly halls ), placesof worship, dance halls, club rooms, passengerstations and terminals of air, surface and otherpublic transportation services, recreation piersand stadia, etc.

2.2.2 Business Buildings - These shall includeany building or part of a building, which is used fortransaction of business ( other than that coveredby 2.2.6 ); for the keeping of accounts and recordsfor similar purposes; offices, banks, professionalestablishments, court houses, and libraries shallbe classified in this group so far as principal func-tion of these is transaction of public businessand the keeping of books and records.

2.2.2.1 Ofice buildings - The buildingsprimarily to be used as an office or for office pur-poses; ‘office purposes’ include the purpose ofadministration, clerical work, handling money,telephone and telegraph operating and operatingcomputers, calculating machines; ‘clerical work’includes writing, book-keeping, sorting papers,typing, filing, duplicating, punching cards ortapes, drawing of matter for publication and theeditorial preparation of matter for publication.

2.2.3 Educational Buildings - These shallinclude any building used for school, college orday-care purposes involving assembly for instruc-tion, education or recreation and which is notcovered by 2.2.1.

2.2.4 Industrial Buildings - These shall includeany building or a part of a building or structure inwhich products or materials of various kinds andproperties are fabricated, assembled or processedlike assembly plants, power plants, refineries, gasp!ants, mills, dairies, factories, workshops, etc.

2.2.5 Institutional Buildings - These shall includeany building or a part thereof, which isused forpurposes, such as medical or other treatment incase of persons suffering from physical and mentalillness, disease or infirmity; care of infants, con-valescents of aged persons and for penal or cor-rectional detention in which the liberty of theinmates is restricted. Institutional buildingsordinarily provide’ sleeping accommodation forthe occupants. It includes hospitals, sanitoria,custodial institutions or penal institutions likejails, prisons and reformatories.

2.2.6 Mercantile Buildings -These shall includeany building or a part of a building which is usedas shops, stores, market for display and sale ofmerchandise either wholesale or retail. Office,storage and service facilities incidental to the saleof merchandise and located in the same buildingshall be included under this group.

2.2.7 Residential Buildings - These shall includeany building in which sleeping accommodation is

provided for normal residential purposes with orwithout cooking or dining or both facilities( except buildings under 2.2.5). It includes one

multi-family dwellings, apartment housesphats ), lodging or rooming houses, restaurants,hostels, dormitories and residential hotels.

2.2.7.1 Dwellings - These shall include anybuilding or. p;i:t occupied by members of single/multi-family units with independent cookingfacilities. These shall also include apartmenthouses ( flats ).

2.2.8 Storage Buildings - These shall includeany building or part of a building used primarilyfor the storage or sheltering of goods, wares ormerchandize, like warehouses, cold storages,freight depots, transity sheds, store houses, gara-ges, hangers, truck terminals, grain elevators,barns and stables.

3. IMPOSED LOADS ON FLOORS DUE TOUSE AND OCCUPANCY

3.1 Imposed Loads - The imposed loads to beassumed in the design of buildings shall be thegreatest loads that probably will be produced bythe intended use or occupancy, but shall not beless than the equivalent minimum loads specifiedin Table 1 subject to any reductions permittedby 3.2.

Floors shall be investigated for both theuniformly distributed load ( UDL ) and the cor-responding concentrated load specified in Table 1and designed For the most adverse effects butthey shall not be considered to act simultaneously.The concentrated loads specified in Table 1 maybe assumed to act over an area of 0.3 x 0.3 m.However, the concentrated loads need notbe considered where the floors are capable ofeffective lateral distribution of this load.

All other structural elements shall be investi-gated for the effects of uniformly distributed loadson the floors specified in Table 1.

NOTE 1 - Where in Table 1, no values are given forconcentrated load, it may be assumed that the tabula-ted distributed load is adequate for design purposes.

NOTE 2 - The loads specified in Table I are equiva-lent uniformly distributed loads on the plan area andprovide for normal effect of impact and acceleration.They do not take into consideration special concentra-ted loads and other loads.

NOTE 3 - Where the use of an area or floor is notprovided in Table 1, the imposed load due to the useand occupancy of such an area shall be determinedfrom the analysis of loads resulting from:

a!b)

weight of the probable assembly of persons;

weight of the probable accumulation of equipmentand furnishing;

4 weight of the probable storage materials; and

4 impact factor, if any.

6

IS : 875 ( Part 2 ) - 1987

TABLE 1 IMPOSED FLOOR LOADS FOR DlFFERENT OCCUPANCIES

(Clauses 3.1, 3.1.1 and4.1.1 )

SLNo.

(1)

OCCYJPANCY CLASSIFICATION

( 2 )

UNIFORMLYDISTRIBUTEDLOAD ( UDL )

( 3 )

kNlma

i ) RESIDENTIAL BUILDINS

a) Dwelling houses:

1) All rooms and kitchens

2) Toilet and bath rooms

3) Corridors, passages, staircasesincluding tire escapes and storerooms

2’0 1’8

2’0 -

3.0 4.5

4) Balconies 3.0

b) Dwelling units planned and execut-cd in accordance with IS : 888S-1979* only:

1) Habitable rooms, kitchens,toi let and bathrqoms

2) Corridors, passages and stair-cases including fire escapes

3) Balconies

C) Hotels, hostels, boarding houses,lodging houses, dormitories,residential clubs:

1)

2)

3)

4)

5)

6)

7)

8)

9)

10)

Living rooms, bed rooms anddormitories

Kitchens and laundries

Billiards room and public loun-gcs

Store rooms

Dining rooms, cafeterias andrestaurants

Oflice rooms

Rooms for indoor games

Baths Lind toilets

Corridors, passages, staircasesincluding fire escapes, lobbies-- as per the floor serviced( excluding stores and the like )but not less than

Balconies

d) Boiler rooms and plant rooms - tobe calcuiated but not less than

I.5

1.5

3.0

2’0

3.0

3.0

5.0 4.5

4.0 2.7

2.5 2.7

3.0 1.8

2’0 -

3’0 4.5

CONCENTRATEDLOAD

( 4 )

kN

1’5 per metre run concen-trated at the outer edge

1’4

1’4

1.5 per metre run concen-trated at the outer edge

1.8

4.5

2.7

Same as rooms to whichthey give access but witha minimum of 4’0


5’0 6.7

( Continued )

7

IS : 875 ( Part 2 ) - 1987

TABLE 1 IMPbED FLOOR LOADS FOR DIFFERENT OCCUPANCIES - Conrd

SL OCCUPANCY CLASSIFICATION UNSFORMLY CONCENTRATEDNo. DISTRIBUTED LOAD

LOAD ( UDL )

(1) (2) (3) (4)kN/ms kN

e) Garages:

Garage floors ( including park-ing area and repair workshops )for passenger cars and vehiclesnot exceeding 2’5 tonnes grossweight, including access waysand ramps - to be calculatedbut not less than

2.5 9.0

Garage floors for vehicles notexceeding 4.0 tonnes grossweight ( including access waysand ramps ) - to be calculatedbut not less than

5’0 9.0

ii) EDUCATIONAL BUILDINGS

a)

b)

4

d)

e)f 1

Lx)h)3

Class rooms and lecture rooms( not used for assembly purposes )

Dining rooms, cafeterias andrestaurants

Offices, lounges and staff rooms

Dormitories

Projection rooms

Kitchens

Toilets and bathrooms

Store rooms

Libraries and archives:

1) Stack room/stack area

2) Reading rooms ( without sepa-rate storage )

3) Reading rooms ( with separatestorage

k)

ml

Boiler rooms and plant rooms - tobe calculated but not less than

Corridors, passages, lobbies, stair-cases including fire escapes - as perthe floor serviced ( without account-ing for storage and projectionrooms ) but not less than

n) Balconies

3’0

3.0t

2.5 2.7

2.0 2.7

5’0 -

3.0 4.5

2.0 -

5.0 45

6’0 kN/ms for a minimumheight of 2’2 m + 2’0kN/m* per metre heightbeyond 2.2 m

4’0

3.0 4.5

4.0 45

40 4.5

2.1

2.7

4’5

4.5

Same as rooms to whichthey give access but witha minimum of 4.0

15 per metre run concen-trated at the outer edge

iii) INSTITUTIONAL BUILDlNGS

a) Bed rooms, wards, dressing rooms,dormitories and lounges

b) Kitchens, laundries and labora-tories

2’0

3.0

1.8

4 5

( Continued )

8

IS : 875 ( Part 2 ) - 1987

TABLE 1 IMPOSED FLOOR LOADS FOR DIFFERENT OCCUPANCIES - Cod

SL OCCUPANCY CLASSIFICATIONNo.

(1) ( 2 )

c) Dining rooms, cafeterias andrestaurants

d) Toilets and bathrooms

e) X-ray rooms, operating rooms,general storage areas -to be cal-culated but not less than

f) Office rooms and OPD rooms

g) Corridors, passages, lobbies andstaircases including fire escapes -as per the floor serviced but not lessthan

h) Boiler rooms and plant rooms - tobe calculated but not less than

j) Balconies

iv) ASSEMBLY BUILDINGS

a) Assembly areas:

1) with fixed seatsz

2) without fixed seats

b) Restaurants ( subject to assembly ),museums and art galleries andgymnasia

c) Projection rooms

d) Stages

e) Office rooms, kitchens and laundries

f) Dressing rooms

g) Lounges and billiards rooms

h) Toilets and bathrooms

j) Corridors, passages, staircasesincluding fire escapes

k) Balconies

m) Boiler rooms and plant roomsincluding weight of machinery

n)- Corridors, passages subject to loadsgreater than from crowds, such aswheeled vehicles, trolleys and thelike. Corridors, staircases and pas-sages in grandstands

UNIFORMLY CONCENTRATEDDISTRIBUTED

LOAD ( UDL )

( 3 )

kN/m’

3.0t

2.0

3’0

2’5

4’0

5’0

LOAD

( 4 )

kN

2.7

-

4’5

2’7

45

4.5

Same as the rooms towhich they give access butwith a minimum of 4.0

1’5 per metre run concen-trated at the outer edge

4’0

5’0

4.0

5'0

5’0

3’0

2’0

2.0

2.0

4’0

Same as rooms to whichthey give access but witha mintmum of 4.0

7’5

5’0

-

3.6

4.5

-

4.5

4.5

1’8

2.7

-

4.5


4’5

4.5

v) BUSINESS AND OFFICE BUILDINGS ( see ulso 3.1.2 )

a) Rooms for general use with separate 2’5storage

2’7

b) Rooms &thout separate storage 4.0 4.5

I Continued )

9

IS : 875 ( Part 2 ) - 1987

TABLE 1 IMPOSED FLOOR LOADS FOR DIFFERENT OCCUPANCIES - Contd

SL OCCUPANCY CLASSIFICATION UNTFORMLY CONCENTRATEDNo. DISTRIBUTED LOAD

LOAD ( UDL )

(1) (2) ( 3 ) ( 4 )kN/m’ kNe

c) Banking halls 3’0 2.7

d) Business computing machine rooms( with fixed computers or similarequipment )

e) Records/files store rooms andstorage space

3’5 4.5

5’0 4.5

f) Vaults and strong room - to becalculated but not less than

5’0 4.5

g) Cafeterias and dining rooms

h) Kitchens

j) Corridors, passages, lobbies andstaircases including fire escapes - asper the floor serviced (excludingstores ) but not less than

k) Bath and toilet rooms

m) Balconies

3.0t 2.7

3.0 2.7

4.0 4.5

2.0


.-.

I.5 per metre run concen-trated at the outer edge

n) Stationary stores

p) Boiler rooms and plant rooms - tobe calculated but not less than

q) Libraries

vi) MERCANTILE BUILDINGS

a) Retail shops

b) Wholesale shops - to be calculatedbut not less than

c) Office rooms

d) Dining rooms, restaurants and cafe-terias

e) Toilets

f) Kitchens and laundries

g) Boiler roooms and plant rooms -to be calculated but not less than

h) Corridors, passages, staircasesincluding fire escapes and lobbies

j) Corridors, passages, staircases sub-ject to loads greater than fromcrowds, such as wheeled vehicles,trolleys and the like

k) Balconies

4’0 for each metre ofstorage height

5’0

see Sl No. ( ii )

4.0 3.6

6’0 4.5

2’5

3’0t

2.0

3’0

5’0

4.0

5.0

2’7

2.7

-

4’5

6.7

4.5

4.5



10

IS : 875 ( Part 2 ) - 1987

TABLE 1 IMPOSED FLOOR LOADS FOR DIFFERENT OCCUPANCIES - Contd

SL OCCUPANCY CLASSIFICATIONNo.

(1) ( 2 )

vii) INDUSTRIAL BUILDTNGS

a)

b)

d

4

e)

f)

9)h)

Work areas without machinery/equipment

Work areas with machinery/equip-ments

1) Light duty 1 To be calcula-2) Medium duty > ted but not3) Heavy duty J less than

Boiler rooms and plant rooms - tobe calculated but not less than

Cafeterias and dining rooms

Corridors, passages and staircasesincluding fire escapes

Corridors, passages, staircases sub-ject to machine loads, wheeledvehicles - lo be calculated but notless than

Kitchens

Toilets and bathrooms

viii) STORAGE BUILDINGS /I

b)

cl

d)

e)

Storage rooms ( other than coldstorage ) warehouses - to be calcu-lated based on the bulk density ofmaterials stored but not less than

Cold storage -- to be calculatedbut not less than

Corridors, passages and staircasesincluding fire escapes --~ as per thefloor serviced but not less than

Corridors, passages subject to loadsgreater than from crowds, such aswheeled vehicles, trolleys and thelike

Boiler rooms and plant rooms

UNIFORMLYDrsTRleUTEDLOAD ( UDL )

( 3 ) ( 4 )

kN/ma kN

2.5

5’07.0

10.0

5.0

3.0t

4.0

5.0

3.0

2’0

CONCENTRATEDLOAD

4.5

4.54.54.5

6.7

2.7

4.5

4.5

4.5

2.4 kN/m* per eachmetre of storage heightwith a minimum of7.5 kN/ma

7.0

5.0 kN/m2 per eachmetre of storage heightwith a minimum of15 kN/m*

9.0

4.0 4.5

5.0 4.5

7.5 4.5

*Guide for requirements of low income housing.tWhere unrestricted assembly of persons is anticipated, the value of UDL should be increased to 4.0 kN/m*.$‘With fixed seats’ implies that the removal of the seating and the use of the space for other purposes is

improbable. The maximum likely load in this case is, therefore, closely controlled.§The loading in industrial buildings ( workshops and factories ) varies considerably and SO three loadings

under the terms ‘light’, ‘medium’ and ‘heavy’ are introduced in order to allow for more economical designs butthe terms have no special meaning in themselves other than the imposed load for which the relevant floor is design-ed. It is, however, important particularly in the case of heavy weight loads, to assess the actual loads to ensurethat they are not in excess of 10 kN/m*; in case where they are in excess, the design shall be based on the actualloadings.

i/For various mechanical handling equipment which are used to transport goods, as in warehouses, workshops,store rooms, etc, the actual load coming from the use of such equipment shall be as-ertained and design shouldcater to such loads.

11

IS : 875 ( Part 2 ) - 1Yar

NOTE 4 - While selecting a particular loading, thepossible change in use or occupancy of the buildingshould be kept in view. Designers should not neces-sarily select in every case the lower loading appropriateto the first occupancy. In doing this, they might intro-duce considerable restrictions in the use of the build-ing at a later date and thereby reduce its utility.

N OTE 5 - The loads specified herein which arebased on estimations, may be considered as thecharacteristic loads for the purpose of limit statemethod of design till such time statistical data areestablished based on load surveys to be conducted inthe country.

N OTE 6 - When an existing building is altered byan extension in height or area, all existing structuralparts affected by the addition shall be strengthened,where necessary, and all new structural parts shall bedesigned to meet the requirements for building there-after erected.

NOTE 7 - The loads specified in the Code does notinclude loads incidental to construction. Therefore,close supervision during construction is essential toeusure that overloading of the building due to loadsby way of stacking of building materials or use ofequipment ( for example, cranes and trucks ) duringconstruction or loads which may be induced by floor tofloor propping in multi-storeyed construction. does notoccur. However: if construction loads were of shortduration, permissible increase in stresses in the case ofworking stress method or permissible decrease in loadfactors in limit state method, as applicable to relevantdesign codes, may be allowed for.

NOTE 8 - The loads in Table 1 are grouped togetheras applicable to buildings having separate principaloccupancy or use. For a building with multiple occu-pancies, the loads appropriate to the occupancy withcomparable use shall be chosen from other occupancies.

NOTE 9 -- Regarding loading on machine roomsinc!uding storage space used for repairing liftmachines, designers should go by the recommendationsof lift manufacturers for the present. Regarding theloading due to false ceiling the same should be con-sidered as an imposed load on the roof/floor to whichit is fixed.

3.1.1 Load Application - The uniformly distri-buted loads specified in Table 1 shall be appliedas static loads over the entire floor area underconsideration or a portion of the floor area which-ever arrangement produces critical effects on thestructural elements as provided in respectivedesign codes.

In the design of floors, the concentrated loadsare considered to be applied in the positions whichproduce the maximum stresses and where deflec-tion is the main criterion, in the positions whichproduce the maximum deflections Concentratedload, when used for the calculation of bending andshear are assumed to act at a point. When usedfor the calculation of local effects, such as crush-ing or punching, they are assumed to act over anactual area of application of 0.3 x 0.3 m.

3.1.2 Loads Due to Light Partitions - In officeand other buildings where actual loads due tolight partitions cannot be assessed at the time ofplanning, the floors and the supporting structuralmembers shall be designed to carry, in addition toother loads, a uniformly distributed load persquare metre of not less than 339 percent of

weight per metre run of finished partitions,subject to a minimum of 1 kN/m2, provided totalweight of partition walls per square metre of thewall area does not exceed 1.5 kN/m2 and thetotal weight per metre length is not greater than4.0 kN.

3.2 Reduction in Imposed Loads on Floors

3.2.1 For Floor Supporting Structuraal Members -Except as provided for in 3.2.1.1, the followingreductions in assumed total imposed loads onfloors may be made in designing columns, loadbearing walls, piers, their supports and founda-tions.

Number of Floors ( In&d- Reduction in Totaling the Roof) to be Carried Distributed Imposed

by Member under Load on all Floors toConsideration be Carried by the

Member underConsideration

( Percent )

12345 to 10Over 10

01020304050

3.2.1.1 NO reduction shall be made for anyplant or machinery which is specifically allowedfor, or in buildings for storage purposes, ware-houses and garages. However, for other buildingswhere the floor is designed for an imposed floorload of 5.0 kN/m” or more, the reductions shownin 3.2.1 may be taken, provided that the loadingassumed is not less than it would have been if allthe floors had been designed for 5.0 kNjmZ withno reductions.

NOTE -In case if the reduced load in the lowerfloor is lesser than the reduced load in the upper floor,then the reduced load of the upper floor will beadopted.

3.2.1.2 An example is given in Appendix Aillustrating the reduction of imposed loads in amulti-storeyed building in the design of columnmembers.

3.2.2 For Reams in Each Floor Level - Wherea single span of beam, girder or truss supportsnot less than 50 m2 of floor at one general level,the imposed floor load may be reduced in thedesign of the beams, girders or trusses by 5 per-cent for each 50 ma area supported subject to amaximum reduction of 25 percent. However, noreduction shall be made in any of the followingtypes of loads:

a) Any superimposed moving load,

12

IS : 875 ( Part 2 ) - 1987

b)

c)

4

Any actual load due to machinery orsimilar concentrated loads,

The additional load in respect of partitionwalls, and

Any impact or vibration.

NOTE - The above reduction does not apply tobeams, girders or trusses supporting roof loads.

3.3 Posting of Floor Capacities - Where a flooror part of a floor of a building has been designedto sustain a uniformly distributed load exceeding3.0 kN/m2 and in assembly, business, mercantile,industrial or storage buildmgs, a permanent noticein the form as shown in the label, indicatingthe actual uniformly distributed and/or concentrat-ed loadings for which the floor has been structu-rally designed shall be posted in a conspicuousplace in a position adjacent to such floor or onsuch part of a floor.

DESIGNED IMPOSED FLOOR LOADING

DISTRIBUTED. . . . . . . . . . . ..kN/mZ

CONCENTRATED, . . . . kN

L-ABEL INDICATING D ESIGNED IMPOSED FL O O R

LOADING

NOTE 1 - The lettering of such notice shall beembossed or cast suitably on a tablet whose leastdimension shall be not less than 0’25 m and located notless than 1.5 m above floor level with lettering of aminimum size of 25 mm.

NOTE 2 - If a concentrated load or a bulk load hasto occupy a definite position on the floor, the samecould also be indicated in the label above.

4. IMPOSED LOADS ON ROOFS

4.1 Imposed Loads on Various Types of Roofs -On flat roofs, sloping roofs and curved roofs, theimposed loads due to use or occupancy of thebuildings and the geometry of the types of roofsshall be as given in Table 2.

4.1.1 Roofs of buildings used for promenade orir.cidental to assembly purposes shall be designedfor the appropriate imposed floor loads given ihTable 1 for the occupancy.

4.2 Concentrated Load on Roof Coverings - Toprovide for loads Incidental to maintenance, unlessotherwise, specified by the Engineer-in-Charge, allroof coverings ( other than glass or transparentsheets made of fibre glass ) shall be capable ofcarrying an incidental load of 0.90 kN concen-trated on an area of 12.5 cm* so placed as to fire-duce maximum stresses in the covering, Theintensity of the concentrated load may be reducedwith the approval of the Engineer-in-Charge,

where it is ensured that the roof coverings wouldnot be transversed without suitable aids. In anycase, the roof coverings shall be capable of carry-ing the loads in accordance with 4.1,4.3, 4.4 andsnow load/wind load.

4.3 Loads Doe to Rain - On surfaces whose posi-tioning, shape and drainage systems are such as tomake accumulation of rain water possible! loadsdue to such accumulation of water and the Impos-ed loads for the roof as given in Table 2 shall beconsidered separately and the more critical of thetwo shall be adopted in the design.

4.4 Dust Load - Jn areas prone to settlementof dust on roofs ( example, steel plants, cementplants ), provision for dust load equivalent toprobable thickness of accumulation of dust maybe made.

.

4.5 Loads on Members Supporting Roof Cover-ings - Every member of the supportingstructure which is directly supporting the roofcovering(s) shall be designed to carry the moresevere of the following loads except as providedin 4.5.1 :

a) The load transmitted to the membersfrom the roof covering(s) in accordancewith 4.1, 4.3 and 4.4; and

b) An incidental concentrated load of 0.90kN concentrated over a length of 12.5 cmplaced at the most unfavourable positionson the member.

NOTE - Where it is ensured that the roofs would betraversed only with the aid of planks and ladders cap-able of distributing the loads on them to Iwo or moresupporting members, the intensity of concentratedload indicated in (b) may be reduced to 0.5 kN withthe approval of the Engineer-in-Charge.

4.5.1 In case of sloping roofs with slope greaterthan lo”, members supporting the roof purlins,such as trusses, beams, girders, etc, may be desig-ned for two-thirds of the imposed load on purlinsor roofing sheets.

5. IMPOSED HORIZONTAL LOADS ONPARAPETS AND BALUSTRADES

5.1 Parapets, Parapet Walls and Balustrades -Parapets, parapet walls and balustrades togetherwith the members which give them structuralsupport shall be designed for the minimum loadsgiven in Table 3. These are expressed as horizon-tal forces acting at handrail or coping level. Theseloads shall be considered to act vertically also butnet simultaneously with the horizontal forces.The values given in Table 3 are minimum valuesand where values for actual loadings are available,they shall be used instead.

5.2 Grandstands and the Like-Grandstands,stadia, assembly platforms, reviewing stands andthe like shall be designed to resist a horizontalforce applied to seats of 0.35 kN per linear metre

13

IS : 875 ( Part 2 ) - 1987

along the line of seats and O-15 kN per linearmetre perpendicular to the line of the seats.These loadings need not be applied simultaneously.Platforms without seats shall be designed to resista minimum horizontal force of O-25 kN/m’ ofplan area.

6. LOADING EFFECTS DUE TO IMPACTAND VIBRATION

6.0 The crane loads to be considered under impos-ed loads shall include the vertical loads, eccentri-city effects induced by vertical loads, impact

factors, lateralacting acrossrespectively.

and longitudinal braking forcesand along the crane rails

6.1 Impact Allowance for Lifts, Hoists and Machi-nery - The imposed loads specified in 3.1 shall beassumed to include adequate allowance for ordi-nary impact conditions. However, for structurescarrying loads which induce impact or vibration,as far as possible, calculations shall be made forincrease in the imposed load, due to impact orvibration. In the absence of sufficient data for

TABLE 2 IMPOSED LOADS ON VARIOUS TYPES OF ROOFS

SL TYPE OF ROOFNo.

(1) (2)

i) Flat, sloping or curved roofwith slopes up to and includ-ing 10 degrees

a) Access provided

( Clause 4.1 )

UNIFORMLY DISTRIBUTEDIMPOSED LOAD MEASUKED

ON PLAN AREA

(3)

1’5 kN/m’

b) Access not provided 0.75 kN/m2except for maintenance

ii) Sloping roof with slope greaterthan 10 degrees

iii) Curved roof with slope of lineobtained by joining spring-ing point to the crown withthe horizontal, greater than10 degrees

For roof membrane sheets or pur-lins-0.75 kN/mZ l e s s 0.02 kN/m’for every degree increase in slopeover 10 degrees

( O;le; 0.52 ya ) kN/m”

y = h/lh = the height of the highest

point of the structuremeasured from its spring-ing; and

I = ;hord width of the roofsingly curved and

shorter of the two sidesif doubly curved

Alternatively, where structuralanalysis can be carried out forcurved roofs of all slopes in asimple manner applying the lawsof statistics, the curved roof shallbe divided into minimum 6 equalsegments and for each segmentimposed load shall be calculatedappropriate to the slope of thechord of each segment as given in( i ) rind ( ii ) above

M INIMUM IMPOSED LOADMEASURED ON PLAN

(4)

3.75 kN uniformly distributedover any span of one metrewidth of the roof slab and 9 kNuniformly distributed over thespan of any beam or truss orwall

1.9 kN uniformly distr ibutedover any span of one metrewidth of the roof slab and 4.5kN uniformly distributed overths span of any beam or trussor wall

Subject to a m i n i m u m o f0.4 kN,W

Subject to a minimum of0.4 kN/m*

NOTE 1 - The loads given above do not include loads due to snow, rain, dust collection, etc. The roof shallbe designed for imposed loads given above or for snow/rain load, whichever is greater.

NOTE 2 - For special types of roofs with highly permeable and absorbent material, the contingency of roofmaterial increasing in weight due to absorption of moisture shall be provided for.

14

IS : 875 ( Part 2 ) - 1987

TABLE 3 HORIZONTAL LOADS ON PARAPETS, PARAPET WALLS AND BALUSTRADES

( Cfause 5.1 )

SLNo.

U SAGE AR E A INTENSITY OF HORIZONTALLOAD, kN/m RUN

(2)

Light access stairs-gangways and the like notmore than 600 mm wide

(3)

0.25

ii) Light access stairs. gangways and thelike, more than 600 mm wide: stairways,landings, balconies and parapet walls( private and part of dwellings )

0.35

iii) All other stairways, landings and balco-nies, and all parapets and handrails toroofs except those subject to overcrow-ding covered under ( iv )

0.75

iv) Parapets and balustrades in place ofassembly, such as theatres, cinemas,churches, schools, places of entertain-ment. sports, buildings likely to be over-crowded

2’25

NOTE - In the case of guard parapets on a floor of multi-storeyed car park or crash barriers provided incertain buildings for fire escape, the value of imposed horizontal load ( together with impact load ) may bedetermined.

such calculation, the increase in the imposed loads 6.2 Concentrated Imoosed Loads with Imuact andshall be as follows:

Structures

For frames supporting liftsand hoists

For foundations, footingsand piers supporting liftsand hoisting apparatus

For supporting structuresand foundations for lightmachinery, shaft or motorunits

For supporting structuresand foundations for reci-procating machinery orpower units

ImpactAllowance

Min100 percen

40 percent

Vibration - Concentrated imposed loads withimpact and vibration which may be due to instal-led machinery shall be considered and providedfor in the design. The impact factor shall not beless than 20 percent which is the amount allow-able for light machinery.

20 percent

50 percent

6.2.1 Provision shall also be made for carryingany concentrated equipment loads whiIe theequipment is being installed or moved for servic-mg and repairing.

6.3 Impact Allowances for Crane Girders - Forcrane gantry girders and supporting columns, thefollowing allowances shall be deemed to cover allforces set up by vibration, shock from slipping orslings, kinetic action of acceleration, and retarda-tion and impact of wheel loads :

Type of Load Additional Load

a) Vertical loads for electric overhead cranes 25 percent of maximum static loads forcrane girders for all classes of cranes

25 percent for columns supporting ClassIJI and Class IV cranes

10 percent for columns supporting Class Iand Class II cranes

No additional load for design of founda-tions

b) Vertical loads for hand operated cranes 10 percent of maximum wheel loads forcrane girders only

(Continued)

15

IS : 813 ( rart L ) - 1Y17

c) Horizontal forces transverse to rails:

1) For electric overhead cranes withtrolley having rigid mast for suspen-sion of lifted weight ( such as soakercrane, stripper crane, etc )

2) For all other electric overhead cranesand hand operated cranes

d) Horizontal traction forces along therails for overhead cranes, either electri-cally operated or hand operated

-10 percen t o f we igh t o f c rab and theweight lifted by the cranes, acting on anyone crane track rail. acting in either direc-tion and equally distributed amongst allthe wheels on one side of rail track

For frame analysis this force shall beapplied on one side of the frame at a timein either direction

-5 percent of weight of crab and the weightlifted by the cranes, acting on anyonecrane track rail, acting in either directionand equally distributed amongst thewheels on one side of rail track

For the frame analysis, this force shall beapplied on one side of the frame at a timein either direction

-5 percent of all static wheel loads

Forces specified in ( c ) and ( d ) shall beconsidered as acting at the rail level and beingappropriately transmitted to the supporting sys-tem. Gantry girders and their vertical supportsshall be designed on the assumption that either ofthe horizontal forces in ( c ) and ( d ) may act atthe same time as the vertical load.

NOTE-&e IS : 807-l!%+ for classification ( ClaSSeS1 to 4 ) of cranes.

6.3.1 Overloading Factors in Crane SupportingSttu twes - For all ladle cranes and chargingcranes, where there is possibility of overloadingfrom production considerations, an overloadingfactor of 10 percent of the maximum wheel load-ing shall be taken.

6.4 Crane Load Combinations - In the absenceof any specific indications, the load combinationsshall be as indicated in the following sub-clauses.

6.4.1 Vertical Loads - In an aisle, where morethan one crane is in operation or has provisionfor more than one crane in future, the followingload combinations shall be taken for verticalloading:

a)

b)

Two adjacent cranes working in tandemwith fu l l load and wi th overloadmgaccording to 6.3( a ); and

For long span gantries, where more thanone crane can come in the span, the girdershall be designed for or.e crane fully loadedwith overloading according to 6.3(a)plus as many loaded cranes as can be

-*Code of practice for design, manufacture, erection

and testing ( structural portion ) of cranes and hoists(first revision ).

accommodated on the span but withouttaking into account overloading accordingto 6.3( a ) to give the maximum effect.

6.4.2 Lateral Surge - For design of columnsand foundations, supporting crane girders, thefollowing crane combinations shall be considered:

a)

b)

6.4.3

For single-bay frames - Effect of onecrane in the bay giving the worst effectshall be considered for calculation of surgeforce, and

For multi-bay frames - Effect of twocranes working one each in any of twobays in the cross-section to give the worsteffect shall be considered I‘or calculationof surge force.

Tractive Force

6.4.3.1 Where one crane is in operation withno provision for future crane, tractive force fromonly one crane shall be taken

6.4.3.2 Where more than one crane is inoperation or there is provision for future crane,tractive force from two cranes giving maximumeffect shall be considered.

N OTE - Lateral surge force and longitudinal trac-tive force actingacross and along the crane rail respec-tively, shall not be assumed to act simultaneously.However, if there is only one crane in the bay, thelateral and longitudinal forces may act together simul-taneously with vertical loads.

7. OTHER LOADS

7.1 Dead Load - Dead load includes the weightof all permanent components of a building includ-ing walls,partitions, columns, floors, roofs, finishes

16

IS:875(Part2)-1987

and fixed permanent equipment and fittings thatare an integral part of the structure. Unit weightof building materials shall be in accordance withIS : 875 ( Part 1 )-1988:

7.2 Wind Load -- The wind load on buildings/structures shall be in accordance with IS : S75( Part 3 )-1988.

7.3 Seismic I;;;;t dfeismic load on buildings/structures , in accordance with

IS : 1893-1984*.

7.4 Snow Load - Snow loading on buildingsshall be in accordance with IS : 875 ( Part 4 )-I 988.

7.1 Special Loads and Load Combinations-Special loads and load combinations shall be inaccordance with 1s : 875 ( Part 5 )-1988.

*Criteria for eartnquake resistant design of structures( fc;ur/h revision ).

A P P E N D I X A

( Clause 3.2.1.2 )

ILLUSTRATIVE EXAMPLE SMOWING REDUCTION OF UNIFORMLY DISTRIBUTEDIMPOSED FLOOR LOADS IN MULTI-STOREYED BUII,DINGS FOR DESIGN

OF COLUMNS

A-l. ‘I he total imposed loads from different floorlevels ( including the roof) coming on the central

Floor loads do.not exceed 5-O kN/m’.

column of a multi-storeved building ( with mixedoccupancy ) is shown in Fig. I. Calculate the

A-l.1 Applying reduction coefficients in accor-dance with 3.2.1, total reduced floor loads on the

reduced imposed load for the design of column column at different levels is indicated along withmembers at different floor levels as given in 3.2.1. Fig. 1.

17

IS:875(Part2)-1987

Floor Actual FloorNo. from Load Coming on

Top ;zfd;ng Columns at DifferentFloors, kN

Loads for which Columns are to beDesigned, kN

( 30 + 40 t- 50 ) (1 - 0.2 ) = 96

(30$4O$50$50)(1-Oo’3)=119

( 3F2Z- 4O + 50 + 50 t 40 ) ( 1 - 0 4 ) =

(3~~50+50+50+40+45)(1-o~4)

( 30 + 40 + 50 + 50 c 40 + 45 + 50 )( l - 0 . 4 ) = 183

( 30 + 40 + 50 + 50 + 40 f 45 + 50 t so)( i -- 0.4) = 213

( 30 + 40 $- 50 + 50 + 40 + 45 + 50 + 50+ 40 ) ( 1 - 0.4 ) = 237

( 30 + 40 + 50 + 50 + 40 + 45 + 50 + 50+ 40 -+ 40 ) ( 1 - 0.4:) = 261

(30+40+5O+50+40+45+50+50+40+40+40)(1-O.5)=237’5<261

:. adopt 261 for design

(30+40+50+50+40+45+50+50-t40+40+40+55) ( l - 0 5 ) = 2 6 5

( 30 + 40 + 50 + 50 + 40 + 45 + 50 + 50H02-y0+40+55+55)(1-O~5)

( 30 + 40 + 50 t 50 + 40 + 45 I- 50 t 50-I- 40 + 40 + 40 + 55 + 55 + 70 )( 1 -05 ) = 327.5

( 30 + 40 + 50 t 50 + 40 + 45 + 50 + 50+40+40-t-40+55+55+70+80)( 1 - 0.5 ) - 367’5

F:G. 1 LOADING D E T A I L S

18



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Regional Offices:


Telephone

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{832 92 95,832 78 58832 78 91,832 78 92

I’rinted at Printograpb, New Delhi, Ph : 5726837

Indian Standard

IS:875 (Part 3) - 1987 ( Renfficd 1997 )

CODEOFPRACTICEFORDESIGNLOADS (OTHERTHANEARTHQUAKE)

FORBUILDINGSANDSTRUCTURES PART 3 WIND COADS

( Second Revision /

Sixth Reprint NOVEMBER 1998

UDC 624-042-41

@J Copyright 1989

BUREAU OF INDIAN STANDARDS MANAK BHAVAN, 9 BAHADUR SHAH ZAFAR MARG

NEW DELHI 110002

Gr I4 Febfuafy 1989

0.

1.

2.

3.

4.

5.

5.1

5.2

5.3

CONTENTS

FOREWORD . . . SCOPE . . .

NOTATIONS . . .

TERMINOLOGY

GENERAL

WIND SPEED AND PRESSURE

Nature of Wind in Atmosphere

Basic Wind Speed

Design Wind Speed ( V, )

. . .

. . .

. . .

. . .

. . .

. . . . . .

. . .

. . .

. . .

. . .

5.3.1 Risk Coefficient ( kr Factor ) . . . . . .

53.2 Terrain, Height and Structure Size Factor ( kt Factor )

5.3.3 Topography ( kS Factor ) . . . . . .

5.4 Design Wind Pressure . . .

5.5 Off-Shore Wind Velocity . . . .-.

6. WIND PRESSURES AND FORCES ON BUILDXNCSISTRUCTURES

6.1 General . . . . . .

6.2 Pressure Coefficients . . . . . . 6.2.1 Wind Load on Individual Members ,.. . . .

6.2.2 External Pressure Coefficients . . . . . . 6.2.3 Internal Pressure Coefficients . . . .

6.3 Force Coefficients . . . . . .

6.3.1 Frictional Drag . . . . . .

6.3.2 Force Coefficients for Clad Buildings ._. . . .

6.3.3 Force Coefficients for Unclad Buildings __. . . .

7. DYNAMIC EP~ECTS . . . . . .

7.1 General 1.. . . . 7.2 Motion Due to Vortex Shedding . . . . . .

7.2.1 Slender Structures . . . . .

IS : 875 ( Part 3 ) - 1987

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4. Gust Factor ( GF ) or Gust Effectiveness Factor ( GEF] Method . . .

8.1 Application . . . . . . . . .

8.2 Hourly Mean Wind . . . . . . . . .

8.2.1 Variation of Hourly Me‘an Wind Speed with Height . . .

8.3 Along Wind Load . . . . . . l . .

APPENDIK A BASIC WIND SPEED AT 10 m HEIGHT FOR SOME IMPORTANT Crrrxs/TowNs . . . . . . . . . . . . . . .

APPENDIX B CHANGES IN TERRAIN CATEGORIES i.. . . . . . .

APPENDIX C EFFECT OF A CLIFF OR ESCARPMENT ON EQUIVALENT HEIGHT ABOVE GROUND ( k3 FACTOR ) . . . . . .

APPENDIX D WIND FORCE ON CIRCULAR SECTIONS . . . . . . . . .

3

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As in the Original Standard, this Page is Intentionally Left Blank

IS t 875 ( Part 3 ) - 1987

Indian Standard

CODEOFPRACTICEFORDESIGNLOADS (OTHERTHANEARTHQUAKE)

FORBUILDINGSANDSTRUCTURES PART 3 WIND LOADS

( Second Revision)

6). FOREWORD

0.1 This Indian Standard ( Part 3 ) ( Second Revision ) was adopted by the Bureau of Indian Standards on 13 November 1987, after the draft finalized by the Structural Safety Sectional Com- mittee had been approved by the Civil Engineer- ing Division Council.

0.2 A building has to perform many functions satisfactorily. Amongst these functions are the utility of the building for the intended use and occupancy, structural safety, fire safety and compliance with hygienic, sanitation, ventilation and daylight standards. The design of the building is dependent upon the minimum requirements prescribed for each of the above functions. The minimum requirements pertaining to the structural safety of buildings are being covered in loading codes by way of laying down minimum design loads which have to be assumed for dead loads, imposed loads, wind loads and other external loads, the structure would be required to bear. Strict conformity to loading standards, it is. hoped, will not only ensure the structural safety of the buildings and structures which are being designed and constructed in the country and thereby reduce the hazards to life and property caused by unsafe structures, but also eliminate the wastage caused by assuming unnecessarily heavy loadings without proper assessment.

0.3 This standard was first published in 1957 for the guidance of civil engineers, designers and architects associated with the planning and design of buildings. It included the provisions for the basic design loads ( dead loads, live loads, wind loads and seismic loads ) to be assumed in the design of the buildings. In its first revision in 1964, the wind pressure provisions were modified on the basis of studies of wind phenomenon and its effect on structures, undertaken by the special committee in consultation with the Indian Mete- orological Department. In addition to this, new clauses on wind loads for butterfly type structures were included; wind pressure coefficients for

sheeted roofs, both curved and sloping were modified; seismic load provisions were deleted ( separate code having been prepared ) and metric system of weights and measurements was adopted.

0.3.1 With the increased adoption of this Code, a number of comments were received on provisions on live load values adopted for. different occupancies. Simultaneously, live load surveys have been carried out in America and Canada to arrive at realistic live loads based on actual determination of loading ( movable and immovable ) in different occupancies. Keeping this in view and other developments in the field of wind engineering, the Structural Safety Sectional Committee decided to prepare the second revision of IS : 875 in the following five parts:

Part 1 Dead loads

Part 2 Imposed loads

Part 3 Wind loads

Part 4 Snow loads

Part 5 Special loads and load combinations

Earthquake load is covered in a separate standard, namely, IS : 1893-1984* which should be considered along with the above loads.

0.3.2 This Part ( Part 3 ) deals with wind loads to be considered when designing buildings, structures and components thereof. In this revision, the following important modifications have been made from those covered in the 1964 version of IS : 875:

a) The earlier wind pressure maps ( one giving winds of shorter duration and another excluding winds of shorter duration )

*Criteria for earthquake resistant design of structures (fourlh recision ).

3

IS : 875 ( Part 3 ) - 1987

b)

4

d)

4

f 1

g)

h)

3

W

have been replaced by a single wind map giving basic maximum wind speed in m/s ( peak gust velocity averaged over a short time interval of about 3 seconds duration ). The wind speeds have been worked out for 50 years return period based on the up- to-date wind data of 43 dines pressure tube ( DPT ) anemograph stations and study of other related works available on the subject since 1964. The map and related recommendations have been provided in the code with the active coopera- tion of Indian Meteorological Department ( IMD ). Isotachs ( lines of equal velocity ) have not been given as in the opinion of the committee, there is still not enough extensive meteorological data at close enough stations in the country to justify drawing of isotachs.

Modification factors to modify the basic wind velocity to take into account the effects of terrain, local topography, size of structure, etc, are included.

Terrain is now classified into four categories based on characteristics of the ground surface irregularities.

Force and pressure coefficients have been included for a large range of clad and unclad buildings and for individual structural elements.

Force coefficients ( drag coefficients ) are given for frames, lattice towers, walls and hoardings.

The calculation of force on circular sections is included incorporating the effects of Reynolds number and surface roughness.

The external and internal pressure coefficients for gable roofs, lean-to roofs, curved roofs, canopy roofs ( butterfly type structures ) and multi-span roofs have been rationalised.

Pressure coefficients are given for combined roofs, roofs with sky light, circular siIos, cylindrical elevated structures, grandstands, etc.

Some requirements regarding study of dynamic effects in flexible slender structures are included.

Use of gust energy method to arrive at the design wind load on the whole structure is now permitted.

0.3.3 The Committee responsible for the revision of wind maps while reviewing available

meteorological wind data and response of structures to wind, felt the paucity of data on which to base wind maps for Indian conditions on statistical analysis. The Committee, therefore, recomm- ends to all individuals and organizations responsible for putting-up of tall structures to ,provide instrumentation in. their existing and new structures ( transmission towers, chimneys, cooling towers, buildings, etc ) at different eleva- tions ( at least at two levels ) to continuously measure and monitor wind data. The instruments are required to collect data on wind direction, wind speed and structural response of the structure due to wind ( with the help of accelerometer, strain gauges, etc ). It is also the opinion of the committee that such instrumentation in tall structures will not in any way affect or alter the functional behaviour of such structures. The data so collected will be very valuable in evolving more accurate wind loading of structures.

0.4 The Sectional Committee responsible for the preparation of this standard has taken into account the prevailing practice in regard to loading standards followed in this country by the various authorities and has also taken note of the developments in a number of other countries. In the preparation of this code, the following overseas standards have also been examined:

a) BSCP 3 : 1973 Code of basic data for design of buildings: Chapter V Loading, Part 2 Wind loads.

b) AS 1170, Part 2-1983 SAA Loading code Part 2 - Wind forces.

c) NZS 4203-1976 Code of practice for general structural design loading for buildings.

d) ANSI A58.1-1972 American Standard Building code requirements for minimum design loads in buildings and other structures.

e) Wind resistant design regulations, A World List. Association for Science Documents Information, Tokyo.

0.5 For the purpose of deciding whether a particular requirement of this standard is complied with, the final value, observed or calculated, expressing the result of a test or analysis, shall be rounded off in accordance with IS : 2-1960*. The number of significant places retained in the rounded off value should be the same as that of the specified value in this standard.

*Rules for rounding off numerical values ( rcoiscd ).

4

IS : 875 ( Part 3 ) - 1987

1. SCOPE

1.1 This standard gives wind forces and their effects ( static and dynamic ) that should he taken into account when designing buildings, structures and components thereof.

1.1.1 It is believed that ultimately wind load estimation will be made by taking into account the random variation of wind speed with time but available theoretical methods have not matured sufficiently at present for use in the code. For this season, static wind method of load estimation which implies a steady wind speed, which has proved to be satisfactory for normal, short and heavy structures, is given in 5 and 6. However, a beginning has been made to take account of the random nature of the wind speed by requiring that the along-wind or drag load on structures which are prone to wind induced oscillations, be also determined by the gust factor method ( see 8 ) and the more severe of the two estimates be taken for design.

A large majority of structures met with in practice do not however, suffer wind induced oscillations and generally do not require to be examined for the dynamic effects of wind, including use of gust factor method, Nevertheless, there are various types of structures or their components such as some tall buildings, chimneys, latticed towers, cooling towers, transmission towers, guyed masts, communication towers, long span bridges, partially or completely solid faced antenna dish, etc, which require investigation of wind induced oscillations. The use of 7 shall be made for i.denti- fying and analysing such structures.

1.1.2 This code also applies to buildings or other structures during erection/construction and the same shall be considered carefully during various stages of erection/construction. In locations where the strongest winds and icing may occur simultaneously, loads on structural members, cables and ropes shall be calculated by assuming an ice covering based on climatic and local experience.

1.1.3 In the design of special structures, such as chimneys, overhead transmission line towers, etc, specific requirements as specified in the respective codes shall be adopted in conjunction with the provisions of this code as far as they are applicable. Some of the Indian Standards available for the design of special structurers are:

IS : 4998 ( Part 1 )-1975 Criteria for design of reinforced concrete chimneys: Part 1 Design criteria ( jirst revision )

IS : 6533-1971 Code of practice for design and construction of steel chimneys

IS : 5613 ( Part l/Set 1 )-I970 Code of practice for design, installation and maintenance of overhead power lines: Part 1 Lines up to and including 11 kV, Section 1 Design

IS : 802 ( Part 1 )-I977 Code of practice for use of structural steel in overhead transmission line towers: Part 1 Loads and permissible stresses ( smmd revision )

IS : 11504-1985 Criteria for structural design of reinforced concrete natural draught cooling towers

NOTE 1 - This standard does not apply to buildings or structures with unconventional shapes, unusual locations, and abnormal environmental conditions that have not been covered in this code. Special investigations are necessary in such cases to establish wind loads and their effects. Wind tunnel studies may aiso be required in such situations.

NOTE 2 - In the case of tall structures with unsymmetrical geometry, the designs may have to be checked for torsional effects due to wind pressure.

2. NOTATIONS

2.1 The following notations shall be followed unless otherwise specified in relevant clauses:

A=

Ae -

Ar, = b =

Cl =

Cl, = tit - c’f -

c, = C PB =

CPl = d-

D =

F Fa 1 Ft - F' =

h X

h, =

Pd -

5

surface area of a structure or part of a Structure; effective frontal area; an area at height z; breadth of a structure or structural member normal to the wind stream in the horizontal plane; force coefficient/drag coefficient; normal force coefficient; transverse force coefficient; frictional drag coefficient; pressure coefficient; external pressure coefficient; internal pressure coefficient; depth of a structure or structural member parallel to wind stream; diameter of cylinder;

force normal to the surface; normal force; transverse force;

frictional force; height of structure above mean ground level; height of development of a velocity profile at a distance x down wind ’ from a change in terrain category;

multiplication factors;

multiplication factor; length of the member or greater horizontal dimension of a building;

design wind pressure;

IS : 875 ( Part 3 ) - 1987

pz = Pe - Pi - R, =

s w

vb -

v, = rz =

W 3

w’ -

X=

e s

a -

B =

9”

+-

t=

c-

design wind pressure at height <; external pressure;

internal pressure; reynolds number; strouhal number; regional basic wind speed; design wind velocity at height 2; hourly mean wind speed at height c; lesser horizontal dimension of a building, or a structural member; bay width in multi-bay buildings;

distance down wind from a change in terrain category; wind angle from a given axis; inclination of the roof to the horizontal; effective solidity ratio; shielding factor or shedding frequency; solidity ratio; a height or distance above the

ground; and average height of the surface roughness.

3. TERMINOLOGY

3.1 For the purpose of this code, the following definitions shall apply.

3.1.1 Angle of Attack -Angle between the direction of wind and a reference axis of the structure,

3.1.2 Breudth - Breadth means horizontal dimension of the building measured normal to the direction of wind.

NOTE - Breadth and depth are dimensions measured in relation to the direction of the wind, whereas length and width are dimensions related to the plan.

3.1.3 Depth - Depth means the horizontal dimension of the building measured in the direction of the wind.

3.1.4 Developed Height - Developed height is the height of upward penetration of the velocity profile in a new terrain. At large fetch lengths, such penetration reaches the gradient height, above which the wind speed may be taken to be constant. At lesser fetch lengths, a velocitv profile of a smaller height but similar to that of the fully developed profile of that terrain category has to be taken, with the additional provision that the velocity at the top of this shorter profile equals that of the unpenetrated earlier velocity profile at that height.

3.1.5 l$+ffective Frontal Area - The projected area of the structure normal to the direction of the wind.

3.1.6 Element of Surface Area - The area of surface over which the pressure coefficient is taken to be constant.

3.1.7 Force Coeficient - A non-dimensional coefficient such that the total wind force on a bbdy is the product of the force coefficient, the dynamic pressure of the incident design wind speed and the reference area over which the force is required.

NOTE - When the force is in the direction of the incident wind, the non-dimensional coefficient will be called as ‘drag coefficient’. When the force is perpendicular to the d&ection of incident wind, the ndn-dimensional coefficient will be called as ‘lift coeficient’.

3.1.8 Ground Roughness - The nature of the earth’s surface as influenced by small scale obstructions such as trees and buildings ( as distinct from topography ) is called ground roughness.

3.1.9 Gust - A positive or negative departure of wind speed from its mean value, lasting for not more than, say, 2 minutes over a specified interval of time.

Peak Gust - Peak gust or peak gust speed is the wind speed associated with the maximum amplitude.

Fetch Length - Fetch length is the distance measured along the wind from a boundary at which a change in the type of terrain occurs. When the changes in terrain types are encountered ( such as, the boundary of a town or city, forest, etc ), the wind profile changes in character but such changes are gradual and start at ground level, spreading or penetrating upwards with increasing fetch length.

Gradient Height- Gradient height is the height above the mean ground level at which the gradient wind blows as a result of balance among pressure gradient force, coriolis force and centri- fugal force. For the purpose of this code, the gradient height is taken as the height above the mean ground level, above which the variation of wind speed with height need not be considered.

Mean Ground Level - The mean ground level is the average horizontal plane of the area enclosed by the boundaries of the structure.

Pressure Coeficient - Pressure coefficient is the ratio of the difference between the pressure acting at a point on a surface and the static pressure of the incident wind to the design wind pressure, where the static and design wind pressures are determined at the height of the point considered after taking into account the geographical location, terrain conditions and shielding effect. The pressure coeSicient is also equal to [ 1 - ( VD/Pz)2], where Vv is the actual wind speed at any point

6

-..,, ._.., ___+. .__.

on the structure at a height corresponding to that of vz.

NOTE - Positive sign of the pressure coefficient indicates pressure acting towards the surface and negative sign indicates pressure acting away from the surface.

Return Period - Return period is the number of years, ‘the reciprocal of which gives the probability of e.xtreme wind exceeding a given wind speed in any one year.

Shielding E$ect - Shielding effect or shielding refers to the condition where wind has to pass along some structure(s) or structural element(s) located on the upstream wind side, before meet- ing the structure or structural element under consideration. A factor called ‘shielding factor’ is used to account for such effects in estimating the force on the’ shielded structures.

Suction - Suction means pressure less than the atmospheric ( static ) pressure and is taken to act away from the surface.

Solidity Ratio - Solidity ratio is equal to the effective area ( projected area of all the individual elements ) of a frame normal to the wind direction divided by the area enclosed by the boundary of the frame normal to the wind direction.

NOTE - Solidity ratio is to be calculated for individual frames.

Y?-eerrain Category - Terrain category means the characteristics of the surface irregularities of an area which arise from natural or constructed features. The categories are numbered in increasing order of roughness.

Velocity Profile - The variation of the horizontal component of the atmospheric wind speed at different heights above the mean ground level is termed as velocity profile.

Tokography - The nature of the earth’s surface as influenced the hill and valley confi- gurations.

4. GENERAL

4.1 Wind is air in motion relative to the surface of the earth. The primary cause of wind is traced to earth’s rotation and differences in terrestrial radiation. The radiation effects are primarily responsible for convection either upwards or downwards. The wind generally blows horizontal to the ground at high wind speeds. Since vertical components of atmospheric motion are relatively small, the term ‘wind’ denotes almost exclusively the horizontal wind, vertical winds are always identified as such. The wind speeds are assessed with the aid of anemometers or anemographs which are installed at meteorological observa- tories at heights generally varying from 10 to 30 metres above ground.

4.2 Very strong winds ( greater than 80 km/h ) are generally associated with cyclonic storms,

IS : 875 ( Part 3 ) - 1987

thunderstorms, dust storms or vigorous monsoons. A feature of the. cyclonic storms over the Indian area is that they rapidly weaken after crossing the coasts and move as depressions/lows inland. The influence of a severe storm after striking the coast does not, in general exceed about 60 kilometres, though sometimes, it may extend even up to 120 kilometres. Very short duration hurricanes of very high wind speeds called Kal Baisaki or Norwesters occur fairly frequently during summer months over North East India.

4.3 The wind speeds recorded at any locality are extremely variable and in addition to steady wind at any time, there are effects of gusts which may last for a few seconds. These gusts cause increase in air pressure but their effect on stability ofthe building may not be so important; often, gusts affect only part of the building and the increased local pressures may be more than balanced by a momentary reduction in the pressure elsewhere. Because of the inertia of the building, short period gusts may not cause any appreciable increase in stress in main components of the building although the walls, roof sheeting and individual cladding units ( glass panels ) and their supporting members such as purlins, sheeting rails and glazing bars may be mqre seriously affected. Gusts can also be extremely important for design of structures with high slenderness ratios.

4.4 The liability of a building to high wind pressures depends not only upon the geographical location and proximity of other obstructions to air flow but also upon the characteristics of the structure itself.

4.5 The effect of wind on the structure as a whole is determined by the combined action of external and internal pressures acting upon it. In all cases, the calculated wind loads act normal to the surface to which they apply.

4.6 The stability calculations as a whole shall be done considering the combined effect, as well as separate effects of imposed loads and wind loads on vertical surfaces, roofs and other part of the building above general roof level.

4.7 Buildings shall also be designed with due attention to the effects of wind on the comfort of people inside and outside the buildings.

5. WIND SPEED AND PRESSURE

5.1 Nature of Wind in Atmosphere - In general, wind speed in the atmospheric boundary layer increases with height from zero at ground level to a maximum at a height called the gradient height. There is usually a slight change in direction ( Ekman effect ) but this is ignored in the code. The variation with height depends primarily on the terrain conditions. However, the wind speed at any height never remains constant and it has been found convenient to resolve its instantaneous magnitude into an average or mean value and a fluctuating component around this

7

IS : 875 ( Part 3 ) - 1987

average vaiue. The average value depends on the averaging time employed in analysing the meteorological data and this averaging time varies from a few seconds to several minutes. The magnitude of fluctuating component of the wind speed which is called gust, depends on the averaging time. In general, smaller the averaging interval, greater is the magnitude of the gust speed.

5.2 Basic Wind Speed - Figure 1 gives basic wind speed map of India, as applicable to 10 m height above mean ground level for different zones of the country. Basic wind speed is based on peak gust velocity averaged over a short time interval of about 3 seconds and corresponds to mean heights above ground level in an open terrain ( Category 2 ). Basic wind speeds presented in Fig. 1 have been worked out for a 50 year return period. Basic wind speed for some important cities/towns is also given in Appendix A.,

5.3 Design Wind Speed ( V, ) - The basic wind speed ( V, ) for any site shall be obtained from Fig. 1 and shall be modified to include the following effects to get design wind velocity at any height ( V, j for the chosen structure:

a) Risk level; b) Terrain roughness, height and size of struc-

ture; and

c) Local topography. It can be mathematically expressed as follows:

where

v, = vb kl k~ ks

V, = design wind speed at any height z in m/s;

kl = probability factor ( risk coeffi. cient ) ( see 5.3.1 );

ks = terrain, height and structure size factor ( see 5.3.2 ); and

ks = topography factor ( see 5.3.3 ).

NOTE - Design wind speep up to IO m height from mean ground level shall be considered constant.

5.3.1 Risk Coej’icient ( kI Factor ) - Figure 1 gives basic wind speeds for terrain Category 2 as applicable at 10 m above ground level based on 50 years mean return period. The suggested life period to be assumed in design and the corresponding kl factors for different class of structures for the purpose of design is given in Table 1. In the design of all buildings and structures, a regional basic wind speed having a mean return period of 50 years shall be used except as specified in the note of Table 1.

5.3.2 Terrain, Height and Structure Size Factor ( k, Factor )

5.3.2.1 Terrain - Selection of terrain cate-

gories shall be made with due regard to the effect

8

of obstructions which constitute the ground surface roughness. The terrain category used in the design of a structure may vary depending on the direction of wind under consideration. Wherever sufficient meteorological information is available about the nature of wind direction, the orientation of any building or structure may be suitably planned.

Terrain in which a specific structure stands shall be assessed as being one of the following terrain categories:

4

b)

Cl

Category 1 - Exposed open terrain with few or no obstructions and in which the average height of any object surrounding the structure is less than 1.5 m.

NOTE - This category includes open sea-coasts and flat treeless plains.

Category 2 - Open terrain with well scattered obstructions having heights generally between I.5 to 10 m.

NOTE - This is the criterion for measure- ment of regional basic wind speeds and includes airfields, open parklands and undeveloped spar- sely built-up outskirts of towns and suburbs. Open land adjacent to sea coast may also be classified as Category 2 due to roughness of large sea waves at high winds.

CategoTy 3 - Terrain with numerous closely spaced obstructions having the size of building-structures up to 10 m in height with or without a few isolated tall structures.

NOTE 1 - This category includes well wooded areas, and shrubs, towns and industrial areas full or partially developed.

NOTE 2 - It is likely that the next higher category than this will not exist in most design situations and that selection of a more severe category will be deliberate.

NOTE 3 - Particular attention must be given to performance of obstructions in areas affected by fully developed tropical cyclones. Vegetation which is likely to be blown down or defoliated cannot be relied upon to maintain Category 3 conditions. Where such situation may exist, either an intermediate category with velocity multipliers midway between the values for Category 2 and 3 given in Table 2, or Category 2 should be selected having due regard to local conditions.

d) Category 4 - Terrain with numerous large high closely spaced obstructions.

NOTE - This category includes large city cen- tres, generally with obstructions above 25 m and well developed industrial complexes.

5.3.2.2 Variation of wind speed with height for di@erent sizes of structures in different terrains ( k,

factor ) - Table 2 gives multiplying factors ( lir ) by which the basic wind speed given in Fig. 1 shall be multiplied to obtain the wind speed at different heights, in each terrain category for different sizes of buildings/structures.

As in the Original Standard, this Page is Intentionally Left Blank

IS : 875 ( Part 3 ) - 1387

The buildings/structures are classified into the following three different classes depending upon their size:

Class A - Structures and/or their components such as cladding, glaxing, roofing, etc, having maximum dimension ( greatest horizontal or vertical dimension ) less than 20 m.

Class B - Structures and/or their com-

ponents such as claddinp, glazing, roofing, etc, having maximum dimension’ ( greatest horizontal or vertical dimension ) between 20 and 50 m.

c1a.U C - Structures and/or their components such as cladding, glazing, roofing, etc, having maximum dimension ( greatest horizontal or vertical dimension ) greater than 50 m.

TABLE 1 RISK COEF’FICIENTS.FOR DIFFERENT CLASSES OF STRUCTURES IN DIFFERENT WIND SPEED ZONES

( Clause 5.3.1 )

CLASS OF STRUCTWZE MEAN PROBABLE k, FACTOR BOB BASIC WIND SPEED DESIGN LIFE OF (m/s ) 0~

STRUCTURE IN r-------- ---_--__7 YEARS 33 39 44 47 50 55

50 -1.0 1’0 1.0 1’0 1.0 1’0

5 0.82 0.76 0.73 0’71 0.70 0’67

25 0.94 0.92 0.91 0.90 0’90 0’89

All general buildings and structures

Temporary sheds, structures such as those used during construction operations ( for example, form- work and falsework ), structures during construction stages and boundary walls

Buildings and structures presenting a low degree of hazard to life and property in the event of failure, such as isolated towers in wooded areas, farm buildings other than residential buildings

Important buildings and structures such as hospitals communication buildings / towers, power plant structures

100 1’05 I ‘06 1’0’: 1’07 I ‘08 1.08

NOTE - The factor kt is based on statistical concepts which take account of the degree of reliability required and period of time in years during which these will be exposure to wind, that is, life of the structure. Whatever wind speed is adopted for design purposes, there is always a probability ( however small ) that it may be exceeded in a storm of exceptional violence; the greater the period of years over which these will be exposure to the wind, the greater is the probability. Higher return periods ranging from 100 to 1 000 years ( implying lower risk level ) in association with greater periods of exposure may have to be selected for exceptionally important structures, such as, nuclear power reactors and satellite communication towers. Equation given below may be used in such cases to estimate k, factors for different periods of exposure and chosen probability of exceedance ( risk level ). The probability level of 0’63 is normally considered sufficient for design of buildings and structures against wind effects and the values of k, corresponding to this risk level are given above.

XN, P kl =

x5O, 0.63

*-L+*{-+ql-P$J z----

A + 4B

where N = mean probable design life of structure in years;

PN - risk level in N consecutive years ( probability that the design wind speed is exceeded at least once in N successive years ), nominal value = 0’63;

X N,P = extreme wind speed for given values of Nand PN; and

x5O, 0’63 = extreme wind speed for N = 50 years and PN = 0’63.

A and B are coefficients having the following values for different basic wind speed zones:

Zone A B

33 m/s 83’2 9’2

39 m/s 84’0 14’0

44 m/s 88,O 18’0

47 m/s 88.0 20’5

50 m/s 88’8 22’8

55 m/s 90.8 27.3

11

LL. ._ ._ _ _ .-. .-

IS : 875 ( Part 3 ) - 1987

HEIGHT

m

(1) IO

:o” 30 50

100 150 200 250 300

350 400 459 500

TABLE 2 k, FACTORS TO OBTAIN DESIGN WIND SPEED VARIATION WITH HEIGHT IN DIFFERENT TERRAINS FOR DIFFERENT CLASSES OF BUILDINGS/STRUCTURES

( ClaUJC 5.3.2.2 )

TEBRAIN CATEQORY 1 CLASS

I---_*--1 A B c

(2) (5) (4) 1’05 1’03 0.99 1.09 1’07 1’03 1’12 1.10 1’06 1’15 1’13 1’09 1-20 1’18 1’14

1’26 1’24 1’20 1’30 1.28 1’24 1’32 1’30 1’26 1’34 1’32 1’28 1’35 1’34 1’30

1’37 1’35 1’31 1’38 1’36 1.32 1’39 1’37 1’33 1’40 1.38 1’34

TERRAIN CATEC+ORY 2 CLbSS

r---_h-_--~ A B c

(5) (6) (7) 1’00 0.98 0.93 1’05 1’02 0.97 1.07 1’05 1’12 1’10 ::z 1’17 1’15 1’10

1’24 1’22 1.17 1’28 1.25 1.21 1’30 1’28 1’24 1’32 1’31 1’26 1.34 1 32 1.28

1’36 1’34 1’29 1’37 1’35 1’30 1’38 1’36 1’31 1’39 1’37 1’32

TEERAIN CATEQO~Y 3 CLASS

c--_-~--_-~ A B c

(8) (9) (10) 0’91 0’88 0’82 0’97 0% 0’87 1’01

:% 0’91

1’06 * 0’96 1’12 1’09 1.02

1’20 1’17 1’10 1’24 1’21 1’15 1’27 1.24 1’18

x 1’26 1’20 1.28 1’22

1’32 1’30 1’24 1’34 1’31 1.25 1’35 1’32 1’26 1~36 1’33 1.28

NOTE 1 - Se6 5.3.2.2 for definitions of Class A, Class B and Class C structures.

NOTE 2 - Intermediate values may be obtained constant wind speed between 2 heights for simplicity.

by linear interpolation, if desired,

TEP.BAIN CATECJORP 4 CLASS

t-_-*---~ A B c

(11) (12) (131 0.80 0.76 0’67 0.80 0’76 0.67 0.80 0’76 0’67 O’Y7 0’93 0’83 1’10 1’05 0’95

1’20 1’15 1’05 1’24 1’20 1.10 1’27 1’22 1’13 1’28 1.24 1’16 1’30 1’26 I.17

1.31 1.27 1’19 1.32 1.28 1’20 1.33 1’29 1’21 1’34 1.30 1’22

It is permissible to assume

5.3.2.3 Terrain categories in relation to the direction of wind - The terrain category used in the design of a structure may vary depending on the direction of wind under consideration. Where sufficient meteorological information is available, the basic wind speed may be varied for specific wind direcion.

5.3.2.4 Changes in terrain categories - The velocity profile for a given terrain category does not develop to full height immediately with the commencement of that terrain category but develop gradually to height ( h, ) which increases with the fetch or upwind distance (x).

a) Fetch and develobed height relationship - The relation between the developed height (h,) and the fetch (x) for wind-flow over each of the four terrain categories may be taken as given in Table 3.

b) For structures of heights greater than the developed height (h,) in Table 3, the velocity profile may be determined in accordance with the following:

i) The les3 or least rough terrain, or

ii) The method described in Appendix B.

5.3.3 Tojography ( ks Factor ) - The basic wind speed Vb given in Fig. 1 takes account of the general level of site above sea level. This does not allow for local topographic features such as hills, valleys, cliffs, escarpments, or ridges which can significantly affect wind speed in their vicinity. The effect of topography is to accelerate wind near the summits of hills or crests‘of cliffs, escarpments or ridges and decelerate the wind in valleys or near the foot of cli%, steep escarpments, or ridges.

12

TABLE 3 FETCH AND DEVELOPED HEIGHT RELATIONSHIP

( C1UUS6 5.3.2.4 )

FE?: (x) DEVELOPED HEIGHT, hx IN METRES

,--__--h_ Terrain Terrain Terrain

----y

Category Terrain

1 Category 2 Category 3 Category 4

(1) (2) (3) (4) (5) 0’2 12 20 35 60

0’5 20 30 35 9.5

1 25 45 80 130

2 35 65 110 190

5 60 100 170 300

10 80 140 25C 450

20 120 200 350 500

50 180 300 400 500

5.3.3.1 The effect of topography will be significzt at a site when the upwind slope (6) is greater than about 3”, and below that, the value of ks may be taken to be equal to 1-O. The value of ks is confined in the range of 1-O to 1.36 for slopes greater than 3”. A method of evaluating the value of ks for values greater than 1.0 is given in Appendix C. It may be noted that the value of ks varies with height above ground level, at a maximum near the ground, and reducing to 1.0 at higher levels.

5.4 Design Wind Pressure - The design wind pressure at any height above mean ground level shall be obtained by the following relationship between wind pressure and wind velocity:

pz = 0.6 r-i

IS : 875 ( Part 3 ) - 1987

where pz = design wind pressure in N/ms at

height z, and

v, - design wind velocity in m/s at height 2.

NOTE - The coefficient 0’6 (in SI units ) in the above formula depends on a number of factors aod mainly on the atmospheric pressure and air temperature. The value chosen corresponds to the average appropriate Indian atmospheric conditions.

5.5 Off Shore Wind Velocity - Cyclonic storms form far away from the sea coast and gradually reduce in speed as they approach the sea coast. Cyclonic storms generally extend up to about 60 kilometres inland after striking the coast. Their effect on land is already reflected in basic wind speeds specified in Fig. 1. The influence of wind speed off the coast up to a distance of about 200 kilometres may be taken as 1.15 times the value on the nearest coast in the absence of any definite wind data.

6. WIND PRESSURES AND FORCES ON BUILDINGS/STRUCTURES

6.1 General - The wind load on a building shall be calculated for:

a) The building as a whole, b) Individual structural elements as roofs and

walls, and c) Individual cladding units including glazing

and their fixings.

6.2 Pressure Coefficients - The pressure coefficients are always given for a particular surface or part of the surface of a building. The wind load acting normal to a surface is obtained by multiplying the area of that surface or its appropriate portion by the pressure coefficient (C,) and the design wind pressure at the height of the surface from the ground. The average values of these pressure coefficients for some building shapes are given in 6.2.2 and 6.2.3.

Average values of pressure coefficients are given for critical wind directions in one or more quadrants. In order to determine the maximum wind load on the building, the total load should be calculated for each of the critical directions shown from all quadrants. Where considerable variation of pressure occurs over a surface, it has been subdivided atid mean pressure coefficients given for each of its several parts.

In addition, areas of high local suction ( negative pressure concentration ) frequently occurring near the edges of walls and roofs are separately shown. Coefficients for the local effects should only be used for calculation of forces on these local areas affecting roof sheeting, glass panels, individual cladding units including their fixtures. They should not be used for calculating force on entire structural elements such as roof, walls or structure as a whole.

NOTE 1 - The coefficients given ’ different tables have k!ey?%tained mainly from me; gurements on models in wind- tunnels, ahd the great majority C.of data available has been obtained in conditions of ielatively smooth flow. Where sufficient field data exists as in the case of rectangular buildings, values have been obtained to allow for turbulent flow.

NOTE 2 - In recent years, wall glazing and cladding design has been a source of major concern. Although of less consequence than the collapse of main structures. damage to glass can be hazardous and cause considerable financial losses.

NOTE 3 - For pressure coefficients for structures not covered here, reference may be made to specialist literature on the subject or advise may be sought from specialists in the subject.

6.2.1 Wind Load on Individual Members - When calculating the wind load on individual strcutural elements such as roofs and walls, and individual cladding units and their fittings, it is essential to take account of the pressure difference between opposite faces of such elements or units. For clad structures, it is, therefore, necessary to know the internal pressure as well as the external pressure. Then the wind load, F, acting in a direction normal to the individual structural element or cladding unit is:

F=(G~---C~~)AP~ where

c De = external pressure coefficient, c Di = internal pressure- coefficient,

A = surface area of structural or cladding unit, and

Pd = design wind pressure.

element

NOTE 1 - If the surface design pressure varies with height, the surface areas of the structural element may be sub-divided so that the specified pressures are taken over appropriate areas.

NOTE 2 - Positive wind load indicates the force acting towards the structural element and negative away from it.

6.2.2 External Pressure Coeficients

6.2.2.1 Walls - The average external pressure coefficient for the walls of clad buildings of rectangular plan shall be as given in Table 4. In addition, local pressure concentration coefficients are also given.

6.2.2.2 Pitched rbofs of rectangular clad buildings - The average external pressure coefficients and pressure concentration coeecients for pitched roofs of rectangular clad building shall be as given in Table 5. Where no pressure concentration coefficients are given, the average coefficients shall apply. The pressure coefficients on the under - side of any overhanging roof shall be taken in accordance with 6.2.2.7.

NOTE 1 - The pressure concentration shall be assumed to act outward ( suction pressure ) at the ridges, eaves, cornices and 90 degree corners of roofs ( see 6.2.2.7 ).

NOTE 2 - The pressure concentration shall not be included with the net external pressure when computing overall loads.

13

km.“_._. _____.__... _...~._

IS : 875 ( Part 3 ) - 1987

TABLE 4 EXTERNAL PRESSURE COEFFICIENTS ( Cpe ) FOR WALLS OF RECTANGULAR CLAD BUILDINGS

( clause 6.2.2.1 ) -

I -

_-

WIND ANGLE

0

BUILDINU HEIGHT RATIO

ELEVATION PLAN Cpe FOR SURFACE / LOCAL Cpe BUILDING

PLAN RATIO

-

A B

--

D

--

+0.7

-0.5

-0.2

-0’5

-0’5

i-0.7

-0’5

-0’2

-I-

+0.7 -0.25 -0.6 -06

-0’5 -0.5 +0.7 -0’1

-i_ -- -- --

+0.7

-0’6

-0’2 -0’6

-0’6 +0*7

-0.6

-0’2

_j.

- 0.3

-0.5

_- -_

.-

--02 -0.8

-0.8 +0’8

.-

I --

--

--

-

I

- .

degrees

0

30

0

30

0

90

0

90

0

90

c

3 a 7 8 1 A -i

D

-0.7

-0.1

I c -0’8 ,’ I

1

: -1.0

-l > -1'1

J

-I } -1’1 J

+<+

--

’ <hd I w2

3 g<;<4

- C

I e&5

A 1 0

-

.-

+0*7

-0’5

-.El

0

-iI_ ‘/ I

cl?-* Cl 0

I!

I<‘<; w

5j

--

$.<.$<4

C

ec?& u 0

D

-0’4

-0’5

-0’7

+0.7

-0’7

+0’8

-_

15

C

b - A Cl 0

D

l<;C+ + 0.8

-0’8

l-o.7

-0’5

-0%

-02

7 > - 1’2 J

3 z_< h<6

w C

ti* 1 e

0

-0’7

-0’1

-I } - 1.2

J

0

90 p,+

( Continued )

14

l!3:875(Part3)-1987

TABLE 4 EXTERNAL PRESSURE COEFFICIENTS ( Cpe ) FOR WALLS OF RECTANGULAR CLAD BUILDINGS - Contd

BUILDING BUILDING ELEVATION PLAN WIND Cpe FOR SUX~FACE LOCAL cpe

HEIGHT PLAN ANGLE I RATIO RATIO 8 A B C D

pggg?z

I 3 0 +0’951 -1’85 -0’9 -0’9 -I -a- w 2

) -1’25 90 -0’8 -0’8 +0’9 -0’85 J

C

0 +0’95 -1.25. -0.7

A I3 90

NOTE - h is the height to caves or parapet, 1 is the greater horizontal dimension of a building and w IS the lesser horizontal dimension of a building.

6.2.2.3 Monoslope roofs of rectangular clad buildings - The average pressure coefficient and pressure concentration coefficient for monoslope ( lean-to ) roofs of rectangular clad buildings shall be as given in Table 6.

6.2.2.4 Canoby roofs with (

$4: Q 1 and

I< &<3 >

- The pressure coefficients are

given in Tables 7 and 8 separately for monopitch and double pitch canopy roofs such as open-air parking garages, shelter areas, outdoor areas, railway platforms, stadiums and theatres. The coefficients take account of the combined effect of the wind exerted on and under the roof for all wind directions; the resultant is to be taken normal to the canopy. Where the local coefficients overlap, the greater of the two given values should be taken. However, the effect of partial closures of one side and or both sides, such as those due to trains, buses and stored materials shall be foreseen and taken into account.

The solidity ratio 4 is equal to the area of obstructions under the canopy divided by the gross area under the canopy, both areas normal

to the wind direction. 4 = 0 represents a canopy with no obstructions underneath. $ - 1 represents the canopy fully blocked with contents to the downwind eaves. Values of C, for intermediate solidities may be linearly interpolated between these two extremes, and apply upwind of the position of maximum blockage only. Downwind of the position of maximum blockage the coefficients for 4 = 0 may be used.

In addition to the pressure forces normal to the canopy, there will be horizontal loads on the canopy due to the wind pressure on any fascia and to friction over the surface of the canopy. For any wind direction, only the greater of these two forces need be taken into account. Fascia loads should be calculated on the area of the surface facing the wind, using a force coefficient of l-3. Frictional drag should be calculated using the coefficients given in 6.3.1.

NOYE - Tables 9 to 14 may be used to get internal and external pressure coefficients for pitches and troughed free roofs for some specific cases for which aspect ratios and roof slopes have been specified. However, while using Tables 9 to 14 any significant departure from it should be investigated carefully. No increase shall be made for local effects except as indicated.

15

TABLE 5 EXTERNAL PRESSURE COEFFICIENTS ( cp, ) FOR PITCHED ROOFS OF RECTANGULAR CLAD BUILDINGS

( Clause 6.2.2.2 )

ik;Il>lD1N0 RlX!F HEIGHT AKaLE RATIO CL

k---W -_1

n- I

0 -0‘8 -0’6 -1’0 -0’6 -2’0

-1’1 -09 -0’7

-0.6 -0’5 -0.6

-0’8 -0.9 -0’8 -0’6 -06

-0’6 - -2’0 1’5 -2’0 -2.0

-2’0 - 1’5 -1’5 -1’2 -1’5 -I.0 - 1’0

I 30 _ I -0’2 -0.5 I -0’8 -0.a I -I’0 l_pp___m / -_ / -1’0

WIND ANGLE 8 WIND ANQLE O 0” 900

EF GH EG FH

- 0’8 -0’4 -0’8 -0.4 -0’9 -0’4 - 0’8 -0’4 -1’2 -0.4 -0’8 -0’6 -0‘4 -0’4 -0’7 -0’6

0 -0.4 -0.7 -0.6 +0*3 -0.5 -0’7 -0’6 +0*7 -0.6 -0’7 -0.6

I

-2’0 - 1’4 -1’4 - 1’0 -0’8

LOCAL COEFFICIENTS

- -1’0 -1’2 - 1’2 - 1’1 -1’1 - 1’1

+o 2 -0’5 -0.8 -0’8 - +0’6 -0’5 -0’8 -0’8

-- - .-

0 I -.0.7 -0’6 -0.9 -0.7 -9.n -3.n -9.n

_. , h ,. 3 I IL

-0’8 -0.6 -0’8 -0’8 r‘5;;<0 I - 1’0

- 1’5 -0.5 -0’8 -0.7 I

-1.5 I

__i. -1.5

5 -0.7 -0% -0’8 -0’8 10 -0.7 -0’6 -0’8 -0’8 Ii.! 1 l$;; / -;.; _:vJ -7’fl -1.5 -1’2

5 -1’2

--oi -0.7 -;.; _~ __ _.

-0’8 -0’7 -0’8 -0.7

18:875(Part3)-1987

TABLE 6 EXTERNAL PRESSURE COEFFICIENTS ( C,, ) FOR MONOSLOPE ROOFS FOR

RECTANGULAR CLAD BUIILDINGS WITH $ < 2

( Clause 6.2.2.3 )

y = h or 0’15 W, whichever is the lesser.

NOTE - Area Hand area L refer to the whole quadrant.

ROOF AIGQLE

OL 0” 45O

WIND ANQLE 13

90” 135O 180”

LOCAL Cpe

Degree H L H L H&LH&L H L H L Hi Hs Lz Ls He Le

em*

3%

%g %$

.I& o, .L .5! a -z E; a%*

<:93 4: 5 -1’0 -0.5 -1.0 -0.9 -1’0 -0’5 -0.9 -1.0 -0’5 -1’0 -2.0 __1’5 -2’0 -1’5 -2’0 -2’0

10 -1’0 -0.5 -1.0 -0.8 -1.0 -0 5

- 1.0 1

-0.6 -1.0 -0.4 -1.0 -2’0 v-1.5 -2.0 -1.5 -2’0 -2.0

15 -o-,9 -0.5 -1’0 -0’7 -0’5 -0.6 -1.0 -0’3 - 1’0 - 1’8 -0’9 -1’8 - 1.4 -2’0 -2’0

20 -0.8 -0.5 -1.0 -0.6 -0.9 ‘-0.5 -0.5 -1.0 -0’2 -1.0 -1.8 -0’8 -1’8 -1.4 -2.0 -2’0

25 -0’7 -0.5 -1’0 -0.6 -0 8. -0.5 -0.3 -0.9 -0.1 -0.9 -1’8 -0.7 -0.9 -0.9 -2.0 -2’0

30 -0’5 -0’5 -1’0 -0.6 -0 8 J

-0’5 -0.1 -0’6 0 -0’6 -1’8 -0-j -0.5 -0.5 -2.0 -2.0

NOTE 2 h is the height to eaves at lower side, I is the greater horizontal dimension of a building and UJ is the lesser horizontal dimension of a building.

18

IS : 875 ( Part 3 ) - 1987

TABLE 7 PRESSURE COEFFICIENTS FOR MDNOSLOPE FREE RQOFS

( Clause 6.2.2.4 )

h

1

Rooy ANGLE ( DECUUUES )

SOLIDITY RATIO MAXINUY ( LARQEST + VE ) AKD MINIMTJIU ( LARGEST - VE ) PRESSURE

COEFFICIENTS

Overall Local Coefficients Coefficients

-

0

5

10

15

20

25

30

0

5

10

15

20

25

All values of d

-

d=O

4-l

4-O

4-l

4=0

4=1

4-o

4-I

b-0

4-l

4-o

4-l

1 BzzzB N

+0-z +0*5 +1*8 +1-l

+0*4 +0’8 +2-l +I’3

+0*5 +1*2 +2’4 +I’6

+0*7 + 1’4 +2’7 +1’8

-l-O’8 +1*7 +2*9 +2*1

+1-o +2-o +3*1 +2’3

+1-z f2’2 +3’2 +2’4 -.

-0’5 -0’6 -1’3 - 1’4

-1’0 -1’2 - 1’8 -1’9

-0.7 - 1.1 - - 1’7 1.8

-1’1 -1.6 -2.2 -2’3

-0.9 -1’5 -2.0 -2.1

-1’3 -21 -2.6 -2.7

-1.1 -1’8 -2’4 -2’5

-1’4 -2’3 -2.9 -3’0

-1.3 -2’2 -2’8 -2’9

-1.5 -2’6 -3’1 -3’2

-1.6 -2’6 -62 -3’2

-1’7 -2’8 -3.5 -3’5

30 4-o -1’8 -3.0 -3.8 -3’6

4=1 - 1’8 -3’0 -3’8 -3.6

NOTE - For monopitch canopies the centre of pressure should be taken to act at 0’3 UJ from the windward edge.

19

KS : 875 ( Part 3 ) - 1987

TABLE 8 PRESSURE COEFFICIENTS FOR FBEE STANDING DOUBLE SLOPED ROOFS

( Clause 6.2.2.4 )

-c,

-CP .-Cn F 10

I

‘I -

-ve ROCF ANGLE +ve ROOF ANGLE

h

- I

Roos Xsa~n 1 1

SOLIDITY MAXIMOX ( LAB~EST+VE ) AYD MINI~X ( LARGEST - VE ) Pn~aacnn

: DEc;lIEZ% ) RATIO CO~FFI~~~NTS

! 1 Overall Local Coefficients

! Coefficients

I / liz%@zl / --“Cl +0*7

+0.5 -i-O% +I’6 / +0’6 +1*7

-15 +06 +1.5 + 0’7 +I’4 - 10 $-O-4 +0’6 +I’4 +0’8 +I’1 -5 +0’3 +1*5 i-0.8 +0’8 7-5 +0.3 :x’,’ .

j Ail values of +0.4 + 1’8 +1*3 +0’4

f 10 +15

! +0*7 +I’8 +1*4 +0*4

i20 I 9

+0*4 +0’6

+0.9 +1.9 +1’4 +0*4

! :x:;

+1*1 +1*9 +1*5 +0.4 3’

:3; +I’2 +1*9 f1’6 -!-0’5 +I’3 +1*9 +1’6 +0*7

/ I -0.7 -

-20 I$=0 -0.9

-0’9 -1’3 -1’6 -0’6

+=1 - 1’2 -1’7 -1’9 -_1’2

o-0 -06 I --:5 /

-0’8 -1’3 -1’6 4-l -0.8

-0’6 -1.1 -1’7 -1’9 - 1’2

-10 I _ “,y * -0’6 1 -08 -0.8

j_ -1.3 -1.5 -0.6 -1’1 -1’7 ’ -1’9 -1:3

$10 ! -0.5 -5

-0’7 -1’3 -1.6 : -0’8 ;

-0.6 -1’5 -1’7 -1’9 -1’4

/ - I

+5 K:, -0’6 / -0.6 -1.4 1 -1’4 -1’1 -0’9 -1’3 -1’8 -1.8 -2’1

+ 10 f=i -0.7 -0’7

1 -1’5 Al.4 -1.4

/ = _ -l’l 1 -1.4 -2’0 -1.8 -2’4

/ + 15 / = ; f=Y

-0’8 j

-0.9 - 1’7 -1’4 -1’8 -1’2 - 1’5 -2’2 -1.9 -2%

i20 $I:, -0’9 -1’ -1’8 - 1.4 -2’0 -1’3 / -1.7 -2’3 -1.9 -3’0

1 I

i-25 $w& 1 -1.0 1 -1.4 i -1’9 - 1’4 -2’0 I -1’4 I -!‘9 -2’4 -2’1 -3’0 _L___ -_ ; ---.-_

i30 $1; -1’0 -1-4 -1’4 -2’0 - 1’4 -2’1

1 I::? _b -2’2 -3.0

Each slope of a duopitch canopy should he able to withstand forces using both the maximum and the mmimurn oefficients, and the whole canopy should be able to support forces using one slope at the maximum coefficient with the Ither slope at the minimum coeffictent. For duopitch canopies the cenrre of pressure should be taken to act at the centre ‘Peach slope.

20

YS : 875 ( Pars 3 ) - Y987

TABLE 9 PRESSURE COEFFICIENTS ( TOP AND BOTTOM ) FOR PXTCHED ROOFS, a +e 3tP

( &uw 6.2.2.4 )

--

9

0

45O

9o”

_-A-

45”

90”

7

-I

j_ I

I I-

-T i

1 T

I 1 E 1

i

L; G z

I__ ---- _____:

J

I c

Roof sIope a 0 30’ e - 0’ - 450, D, D’, E, E’ :x1:

length 9 = 90”, D, D’, E, E’ prr !engzh

b’, thereafter Cp = 0

D 1 D

I I

I 0’6 ! -1’0

0.1 ; -0.3

-0’3 j -C’4

, ----I

1 1 End Surfaces

E

) E’ j c j c’ / c; I

/ j

I - -05 / -0.3 1

! -0’6 / i I -0.3 /

1 -0.3 1 -0.4 I -0*3 / 0.8 / : I 0’3

-7

I

.j_

G’

I

Forj : Cp top = -i’O; Cp bottom = -0.2

Tangentially acting friction: ROOo ip 0’05 pdbd

21

IS I 875 ( Part 3 ) - 1387

i

.-

TABLE 10 PRESSURE COEFFICIENTS ( TOP AND BOTTOM ) FOR PITCHED FREE ROOFS, a = 300 WITH EFFECTS OF TRAIN OR STORED MA’I’BRIALS

( Clause 6.2.2.4 )

! ,

b:5C

I

I I

!

-

.I-. _G__ L I c

E

- --_

&d --I

Roof slope LY = 300 Efftctz of trains or stored

materials: 0 a 0” -45”, or 135” -180”,

D, D’. E, F’ full lqngth 6 - ;;,.$, D , E, E part

& = 0 b’, thereafter

PRESSURE COEFFICIENTS, cp

cl “/

End Surfaces

D D’ E E’

c c G G’

0” 0’1 0’8 -0’7 0’9

45O -0’1 0’5 -0’8 0’5

90” -0’4 -0’5 -0’4 -0’5 -0’3 0’8 0’3 -0’4

180” -0’3 -0’6 0’4 -0’6

-

45” Forj : Cp top = - 1’5; C, bottom Q 0’5

go0 Tangentially acting friction: &a” = 0’05 pdbd

22

-a.-%“---_-_-_“_... _. _

IS I 875 ( Part 3 ) - 1987

TABLE 11 PRESSURE COEFFICIENTS (TOPANDBOTTOM)FORPlTCHEDF~~ BOOFS,am 10"

( Clause 6.2.2.4)

b=Sd

f b’=d

1

Roof slope (L = IO” 8 = 0” - 45”, D, D’, E, E’ full length 0 = 90°, D, D’, E, E’ par1 length b’,

thereafter Cp = 0

PRESSURE COEFFICIENTS, CD

e End Surfaces

D D’ E E’

c I

C G 1 G

-- -~.

00 -1.0 03 -0.5 0.2 ,

45" -0'3 0.1 -0'3 0’1

90” -0.3 0 -0.3 0 -0'4 0.8 09 -0.6

-

0" Forf: Cp top = -11’0; Cp bottom = 0’4

0” - 90° Tangentially acting friction, RIO’ = O”1 pdbd

23

TABU I2 PRESSURE COEFFICIFiNTS (*OP AND BOTTOM ) FOR PITCRBD FBE ROOFS ir - 10” WITH EFFECTS OF TRAIN OR STORED MATJZItIAL8

( CIaw 6.2.2.4 )

i i

!

-T h’=O$t h _A_

Roof slope m - IO0 EAacts of trains or stored materials: e-o.=- 45’,or 135’ - 180°,

D, D’, E, E’ full length 0 = 90*, D, D’, E, E’ part length b’,

thereafter CD = 0

G i

!

1 I / 1

-0’4 0.8 0’3

! I

G’

-0%

i I

I

i

0” ’ ForJ: I;, top = -15; Cp bottom = 0.9

0” - I!$” / Tangentially acting friction: R,o” .= 0.1 p&j

24

1sr875(Part3)-1987

TABLE 13 EXTERNAL PRESSURE COEFTZCXENTS FOR TROUGHED FRER ROOPS, a = IO”

( Clause 6.2.2.4 )

Roof slope a - 10” 9 = 0” -45”, D. D’, E. E’ full

iength A = 90*, D,_ D’, E, E’ Fatt length

b’, thereafter Cp I 9

0”

4Y

90”

I

D D’ 1 E ,

/ E’ I /

0’3 -0’7 I

0’2 ! -0’9 I

0 -0’2 ,

0’1 j -0’3 /

-0’1 0.1 -0’1 I 0‘1

0” Forf : CD top = 0’4; Cp bottom = - i-1

0” -90 Tangentially acting friction Rgo” = G’i &bi

P&EssUnE cOEFFICIEK?K3, cp

25

ISr875( Part3)-1987

TAtWE 14 PRESSURE COEFFICIENTS ( TOP AND BOTTOM ) FOR TROUGHED FREE ROOFS, a = IO” WITH EFFECTS OF TRAINS OR STORED MATERIALS

( Clause 6.2.2.4 )

b= 5d

E

T f Lm i------i

Roof slope (I = 10” Effects of trains or stored

materials: 13 = 0” - 450, or 135” - 180”,

D, D’, E, E’ full length 13 = go”, D, D’, E, E’, part

length b’ thereafter Cp = 0

e

00

45O

90°

180”

0”

O”- 180’

D

-0’7

-0’4

-0.1

-0’4

PRESSURE COEFFICIENTS, Cp

D’ E E’

0’8 -0’6 0’6

0’3 -0’2 0’2

0’1 -0’1 0’1

-0.2 -0.6 - 0’3

Forf: Cp top = - 1’1; CD bottom = 0’9

Tangentially acting friction: &,o’ = 0’1 pabd

26

6.2.2.5 Curved roofs - For curved roofs, the external pressure coefficients shall be as given in Table 15. Allowance for local effects shall be -made in accordance with Table 5.

6.2.2.6 Pitched and saw-tooth roofs of multi- span buildings - For pitched and saw-tooth roofs of multi-span buildings, the external average pressure coefficients and pressure concentration coefficients shall be. as given in Tables 16 and 17 respectively. provided that all spans shall be equal and the height to the eaves shall not exceed the span.

NOTE- Evidence on multi-span buildings is fragmentary; any departure given in Tables 16 and 17 should be investigated separately.

6.2.2.7 Pressure coeficients on overhangs from roofs - The pressure coefficients on the top overhanging portion of the roofs shall be taken to be the same as that of the nearest top portion of the non-overhanging portion of the roofs. The pressure coefficients for the underside surface of the overhanging portions shall be taken as follows and shall be taken as positive if the overhanging portion is on the windward side:

a) 1.25 if the overhanging slopes,

b) 1.00 if the overhanging isShorizontal, and

c) 0.75 if the overhanging slopes upwards.

For overhanging portions on sides other than the windward side, the average pressure coefficients on adjoining walls may be used.

6.2.2.8 Cylindrical structures - For the purpose of calculating the wind pressure distribution around a cylindrical structure of circular cross- section, the value of external pressure coefficients given in Table 18 may be used provided that the Reynolds number is greater than 10 000. They may be used for wind blowing normal to the axis of cylinders having axis normal to the ground plane ( that is, chimneys and silos ) and cylinders having their axis parallel to the ground plane ( that is, horizontal tanks ) provided that the clearance between the tank and the ground is not less than the diameter of the cylinder.

h is height of a vertical cylinder or length of a horizontal cylinder. Where there is a free flow of air around both ends, h is to be taken as half the length when calculating h/D ratio.

In the calculation of the resultant load on the periphery of the cylinder, the value of C,t shall be taken into account. For open ended cylinders, C,i shall be taken as follows:

a) 0.8 where h/D is not less than 0.3, and

b) 0.5 where h/D is less than 0.3.

6.2.2.9 Roofs and bottoms of cylindrical elevated structures - The external pressure coefficients for roofs and bottoms of cylindrical elevated structures shall be as given in Table 19 ( see also Fig. 2 ).

IS : 875 ( Part 3 ) - 1987

The total resultant load (P) acting on the roof of the structure is given by the following formula:

P = 0.785 D’ ( _!q - C,, pa)

The resultant of Pfor roofs lies at 0.1 D from the centre of the roof on the windword side.

6.2.2.10 Combined roofs and roofs with a sky light - The average external pressure coefficients for combined roofs and roofs with a sky light is shown in Table 20.

6.2.2.11 Grandstands - The pressure coefficients on the roof ( top and bottom ) and rear wall of a typical grandstand roof which is open on three sides is given in Table 21. The pressure coefficients are valid for a particular ratio of dimensions as specified in Table 21 but may be used for deviations up to 20 percent. In general, the maximum wind load occurs when the wind is blowing into the open front of the stand, causing positive pressure under the roof and negative pressure on the roof.

6.2.2.12 Upper surface of round silos and tanks - The pressure coefficients on the upper surface of round silos and tanks standing on ground shall be as given in Fig. 2.

6.2.2.13 Spheres - The. external pressure coefficients for spheres shall be as given in Table 22.

6.2.3 Internal Pressure Coejicients - Internal air pressure in a building depends upon the degree of permeability of cladding to the flow of air. The internal air pressure may be positive or negative depending on the direction of flow of air in relation to openings in the buildings.

6.2.3.1 In the case of buildings where the claddings permit the flow of air with openings not more than about 5 percent of the wall area but where there are no large openings, it is necessary to consider the possibility of the internal pressure being positive or negative. Two design conditions shall be examined, one with an internal pressure coefficient of +0.2 and another with an internal pressure coefficient of -0.2.

The internal pressure coefficient is algebrai- cally added to the external pressure coefficient and the analysis which indicates greater distress of the member shall be adopted. In most situations a simple inspection of the sign of external pressure will at once indicate the proper sign of the internal pressure coefficient to be taken for design.

NOTE - The term normal permeability relates t* the flow of air commonly aft‘orded by claddings not only through open windows and doors, but also through the slits round the closed winc’ows 2nd doors and through chimneys, ventilators and through the joints between roof coverings, the total open area being less than 5 percent of area of the walls having the openings.

TABLE 15 EXTERNAL PRESSURE COEFFICIENTS FOR CURVED ROOFS

( Clause 6.2.2.5 )

l------~-----l a) Roof springing from ground level

b) Roof on elevated structure

-0.6

Values of C, Cl and C2

-CL_

0'1 -0’8 +0*1 _-

0.2 -0’9 +0*3 ___-

03 -1.0 +0*4 p_--

0’4 -1’1 +06 -- -~

0.5 -1’2 +0.7

c2

-0’8

-0.7 .~

-0.3 jp

+0*4

i-o.7

NOTE - fihen the wind is blowing normal to gable ends, Cpe may be taken as equal to -0.7 for the full width of the roof.over a length of l/2 from the gable ends and -0.5 for the remaining portion.

rCENTRAL HALF (Cl

fiGkIfCiN OF ROOF EEL THIS LINE TO BE TREAIED AS AN EXTENSION of VERTICAL SUPPORTS

c) Doubly curved roofs

7 0 0.6 --

GUARTE 4 i

R

. .___I.__

ISr875(Part3)-19a7

TABLE 16 EXTERNAL PRESSURE COEFFICIENTS ( C b i’OR PlTCHED ROeFS OP MULTISPAN BUILDINGS (ALL SPANS EQ&lp, WITH h > w’

( Ckusc 6.2.2.6 )

I w’ J_ w’ J_ w’ _1_ w’ _I_ w’ I w* 1 I- -l- I-

ROOF PLAN y=h or 0-1~ WHICHEVER IS LESS h,= h,=h

i I

SECTION

ROOF WIND FIRST SPAN FIRST OTHER END SPAN ANR LE ANQLE INT~YIcDIATE INT~R~~EDIATE

SPAN SPAN

-- -- c----t

a e --7 4 C d m n x 2

degrees degrees

5 0 -0’9 -0.6 -0’4 -0’3 -0’3 -0’3 -0.3 -0’3 I

10 -1’1 -0.6 -0’4 -0’3 -0’3 -0.3 -0’3 -0’4 I

20 -0’7 -0’6 -0’4 -0’3 -0’3 -0’3 -0.3 -0.3 \

30 -0.2 -0’6 -0.4 -0’3 -0.2 -0’3 -0’2 -0’5 )

45 +0*3 -0.6 -0.6 -0’4 -0’2 -0.4 -0’2 -0.5 J

Distance r---- -- h-P---- __- Roof Wind hx ha h3

Angle Angle d;reea 8

degrees

up to 45 90 -0’8 -0’6 -0’2

LOCAL ~RFPIOUNT

-2’0 -1’5

Frictional drag: When wind angle 0 - O’, horizontal forces due to frictional drag are allowed for in the aboye values; and

when wind angle 0 = 90°, allow for frictional drag in accordance with 6.3.1.

NOTE - Evidence on these buildings is fragmentary and any departure from the casu given should ba investigated reparately.

29

L_ .._ . ._.-

IS : 875 ( Part 3 ) - 1987

TABLE 17 EXTERNAL PRESSURE COEFFICIENTS C,e FOR SAW-TOOTH ROOFS OF MULTI- SPAN BUILDINGS (‘ALL SPANS EQUAL ) WITH h > w’

( Clause 6.2.2.6 )

ROOF PLAN Y =hor 0’1 UI which-

ever is the less hl=hB = h

SECTION

WIND FIRST SPAN FIRST OTHER END SPANS LOCAL COEFFICIENT ANC+LE INTER~~~EDIATE INTERMEDIATE

e SPAN SPANS c----Y r--hw-y r---h_-~ C--h--7

a b c d m R x t

degrees

0 +0’6 -0.7 -0’7 -0.4 -0.3 -0’2 -0.1 -0’3 1 -1’5

180 -0’5 -0.3 -0.3 -0.3 -0.4 -0.6 J -2’0

-0’6 -0’1

DISTANCE c------------ -+.L----_-----~

WIND h ha ha ANGLE 0

degrees

90 -0.8 -0% -0’2

210 Similarly, but handed

Frictional drag: When wind angle 0 = O’, horizontal forces due to frictional drag values; and

are allowed for in the above

when wind angle 8 I 90”, allow for frictional drag in accordance with 6.3.1.

NOTE - separately.

Evidence on these buildings is fragmentary and any departures from the cases given should be investigated

30

18:875(P8rt3)-1987

TABLE I8 EXTERNAL PRESSURE DISTRIBUTION COEFPICIENTS AROuN6 CTLiNDkWWL sTRucTURm3 ’ ( CIaucs 6.2.2.8 )

POSITION OF PEBIPHERY, 0 IX DEQREEB

PRESSUI~E COEFFICIENT, Cm

h/D = 25 h/D = 7

0 1’0 1.0

15 O-8 0’8

30 0.1 0’1

45 -0’9 -0’8

60 -1’9 -1’7

75 -2’5 -2.2

90 -2’6 -2’2

105 - 1.9 -1’7

120 -0’9 -0’8

135 -0.7 -0.6

150 -0’6 -0.5

165 -06 -0’5

180 -0.6 -0.5

-

-

I h/D = 1

1’0

0’8

0’1

-0’7

-1;2

- 1.6

-1’7

-1.2

-0.7

-0.5

-0’4

-0’4

-0’4 I --

31

IS -I 875 ( Part 3 ) - 1987

T-LB 19 =TBRNAL PRESSURE COE@FICIENTS FOR ROOFS AND BOTTOMS OF CYLINDRICAL BUILDINGS

( Clause 6.2.2.9 )

P OIREC?TION Of WIN0

(bl

(cl

COS~FICIE~ OF EXTERXAL PREBSURE, Cps

STRUCTURE ACCOBDIITG TO SEAPE

a,budc d

HID Roof (z/H) -1 Roof

0’5 -0.65 1’00 -0’75

130 -1’00 1’25 -0’75

I 2.00 - 1’00 1’50 -0’75

Total force acting on the roof of the structure, P 1 0’785 Da ( pi - CpePd )

The resultant of P lier ecceotricdly, # a O’ID

_

-

Bottom

-0’8

-0.7

-0.6

32

IS:875(Part5)-1987

TABLE 28 EXTERNAL PRESSURE COEFFICIENTS, Cw FOR COMBINED ROOFS AND ROOF’S WITH A SKY LIGHT

( Clause 6.2.2.10 )

a) Combined Roofs

-0.8

POETION DIRECTION 1 DIRECTION 2

a From the Diagram

b

I candd

VALUE0 OP cpe

Cpe = -0’5, - < 1’5 hr

-0’4

Cpe = -0’7, _!!!_ > I.5 he

See Table 5

see 6.2.2.7

( Confinurd )

33

IS : 875 ( Part 3 ) - 1987

TABLE 20 EXTERNAL PRESSURE COEFFICIENTS, -Cpe FOR COMBINED ROOFS AND ROOFS WITH A SKY LIGHT - Contd

b) .Roofs with a Sky Light

WIN0

PORTION

Ge I

b; ; b, bl < bs

0 b a and b

---

-0.6 $0’7 See Table for combined roofs

34

IS t 875 ( Part 3 ) - 1987

TABLE 21 PRESSURE COEFFICIENTS AT TOP AND BOTTOM ROOF OF GRAND STANDS OPEN THREE SIDES ( ROOF ANGLE UP TO 5” )

( Clause 6.2.2.11 )

( A : b : I= 0.8 : 1 : 2’2 )

G 1 I

0 H

i-----b4 ( Shaded area to scale )

1

0

0”

*

45O

135”

-

/ 180” i -0.6

KM

777

7 Mw

FRONT AND BACK OF WALL

8 3 x L

---

0* -l-O’9 -0.5 +0.9

-

45” +0.8 -0’6 +0*4

135O - 1’1 +0’6 - 1.0

-_

180~ -0.3 co.9 -0’3

-

60” ‘Mw’ - CpofK= -1’0

60” ‘Mw’ - c, Of.3 = + 1’0

--

M

-0.5

-0’4

+0*4

+0.9

TOP AND BOTTOM OF ROOF

B c D E

-- -.-

+0*9 -1.0 +0.9 -0.7

$0’7 -0’7 -CO’4 -0.5

-1.1 -0’7 -1’0 -0.9

N_

-0’3 -0.6 -0.3 -0’6

+0’9

~-

+0’8

CO’7 f0’9

--

-0’5 f0’3

-0.9 -1’0

--.-

-0’6 -0’3

45O

45”

‘MR’ - cp ( top ) = -2.0

-

‘MB’ - Cp ( bottom ) = + 1’0

35

I8 : 875 ( Part 3 ) - 1987

FIQ. 2

T- 1.5 j.0 a 0.5

h

0.20 <h <30 tand c 0.2

I,,, /I , ,, , , ,, _ , , ,,., , ,,, , ,

0 ._.

SECTION AA ---I

PLAN ( For Force Coefficient Corresponding to Shell Portion, see Table 23 ).

EXTERNAL PRESSURE COEFFICIENT ON THE UPPER ROOF SURFACE OF SINQULAR STANDING ON ‘1 :HE GROUND

6.2.3.2 Buildings with medium and large ojenings - Buildings with medium and large openings may also exhibit either positive or negative internal pressure depending upon the direction of wind. Buildings with medium openings between about 5 to 20 percent of wall area shall be examined for an internal pressure coeffi- Fient of +0*5 and later with an internal pressure coefficient of -0.5, and the analysis which produces greater distress of the members shall be adopted. Buildings with large openings, that is, openings larger than 20 percent of the wall area shall be examined once with an internal pressure coefficient of $-O-7 and again with an internal pressure coefficient of -0.7, and the analysis which produces greater distress on the members shall be adopted.

Buildings with one open side or opening exceeding 20 percent of wall area may be assumed to be subjected to internal positive pressure or suciion similar to those for buildings with large openings. A few examples of buildings with one sided openings are shown in Fig. 3 indicating values of internal pressure coefficients with respect to the direction of wind.

6.2.3.3 In buildings with roofs but no walls, the roofs wiil be subjected to pressure from both inside and outside and the recommendations shall be as given in 6.2.2.

36

ChtCr;t~~

6.3 Force Coefficients - The value of force coefficients apply to a building or structure as a whole, and when multiplied by the effective. frontal area A, of the building or structure and by design wind pressure, pd gives the total wind load on that particular building or structure.

F - Ci A, ~a

where F is the force acting in a direction specified in the respective tables and Ci is the force coeficient for the building.

RiOTE 1 - The value of the force coefficient differs for the wind acting on different faces of a building or structure. In order to determine the critical load, the total wind load should be calculated for each wind direction.

NOTE 2 - If surface design pressure varies with height, the surface area of the building/structure mav be sub-divided so that specified pressures are taken over appropriate areas.

NOTE 3 - In‘tapered buildinq/structures, the force coefficients shall be applied aiier sub-dividing the building/structure into suitable number of strips and the load on each strip calculated individually, taking the area of each strip as Ae.

NOTE 4 - For force coefficients for structures not. covered above, reference may be made to specialist literature on the subject or advise may be sought from specialists in the subject.

iS I 875 ( Part 3 ) - 1987

TARLE !Z2 =TRRNAL PRESSURE DISTRIRUTION COEFFICIENTS AROdND SPHERICAL STRUCTURES

( Chse 6.2.2.13 )

1-

0 4-1'0

15 +0.9

30 -to*5

45 -0’1

60 -0.7

75 --I’1

90 - 1.2

105 - 1’0

120 -0.6

135 -0.2

150 +0*1

165 +0*3

180 +0*4

-

REMAIIKS

Ct = 0.5 for Dl;d < 7

= 0.2 for DVa > 7

6.3.1 Frictional Drag - In certain buildings of special shape, a force due to .frictional drag shall be taken into account in addition to those loads specified in 6.2. For rectangular clad buildings, this addition is necessary only where the ratio

C,’ - 0.02 for surfaces with corrugations across the wind direction, and

Cf’ = 0.04 for surfaces with ribs across the wind direction.

d d - or

h F is greater than 4. The frictional drag For other buildings, the frictional drag has

force, F’, in the direction of the wind is given by been indicated, where necessary, in the tables of

the following formulae: pressure coefficients and force coefficients.

Ifh< b,F’=C,‘(d-4h)b@, s Cr’ ( d - 4h ) 2 hi&, and 6.3.2 Force Corficients for Ciad Buildings

if A > b, F’ - “;‘&-j 4b ) bjd - 4b ) 2 h&.

6.3.2.1 Clad buildings of uniform section -

The first term in each case gives the drag on The overall force coefficients for rectangular clad b ur ‘ld’

the roof and the second on the walls. The value mgs of uniform section with Aat roofs in

of Cr’ has the following values: uniform flow shall be as given in Fig. 4 and for other clad buildings of uniform section ( without

C,‘ - 0.01 for smooth surfaces without corru- projections, except-where otherwise sho& ) shall gations or ribs across the wind direction, be as given in Table 23.

37

IS : 875 ( Part 3 ) - 1987

(C) For F = I, use average values

Arrows indicate direction of wind.

FIG. 3 LARGE OPENINQ IN-BUILDINGS ( VALUES OF COEFFICIENTS OF INTERNAL PRESXJRE ) WITM TOP CLOSED

6.3.2.2 Buildings of circular shajcs - Force surface varying linearly from a maximum of l-7’ coefficients for buildings circular cross-section Cr at the up wind edge to 044 Ci at the down shapes shall be as given in Table 23. However, more precise estimation of force coefficients for

wind edge.

circular shapes of infinite length can be obtained The wind load on appurtenances and supports

from Fig. 5 taking into account the average for hoardings shall be accounted for separately by

height of surface roughness E. When the length using the appropriate net pressure coefficients.

is finite, the values obtained from Fig, 5 shall be Allowance shall be made for shielding effects of

reduced by the multiplication factor K ( see also one element or another.

Table 25 and Appendix D ). 6.3.2.4 Solid circular shajes mounted on a

6.3.2.3 Lox walls and hoardings - Force surface - The force coefficients for solid circular

coefficients for low walls and hoardings less than shapes mounted on a surface shall be as given in

15 m high shall be as given in Table ‘21 provided Fig. 6.

the height shall be measured from the ground to 6.3.3 Force Coejicients for Unclad Buildings the top of the walls or hoarding, and provided that for walls’ or hoardings above ground the

6.3.3.1 General - This section applies to.

clearance between the wall or hoarding and the permanently unclad buildings and to frameworks

ground shall be not less than 0.25 times the verti- of buildings while temporarily unclad. In the case

cal dimension of the wall or hoarding. of buildings whose surfaces are well rounded, such as those with elliptic, circular or ovoid cross-

To allow for oblique winds, the design shall sections, the total force can be more at wind also be checked for net pressure normal to the speeds much less than the maximum due to

38

ztransition in the nature of boundary layer OII them. Although this phenomenon is well known in the case of circular cylinders, the same phenomenon exists in the case of many other well-rounded :structures, and this possibility must be checked.

6.3.3.2 Individual members

a) The coefficients refer to the members of infinite length. For members of finite length, the coefficients should be multiplied by a factor K that depends on the ratio I/b where 1 is the length of the member and 5 is the width across the direction or wind. Table 25 gives the required values of K. The foliowing special cases must be noted while estimating K.

b)

i) Where any member abuts onto a plate or wall in such a way that free flow of air around that end of the member is pre- vented, then the ratio of l/b shall be doubled fat the purpose of determining K; and

ii) When both ends of a member are so

c)

d)

t

c f

h -_=a b

\\I 701 i I I

IS : 875 ( Part 3 ) - 1987

obstructed, the ratio l/b shall be taken as infinity for the purpose of determining K_

Flat-sided members - Force coefficients’ for wind normal to the longitudinal axis of flat-sided structural members shall be as given in Table 26.

The force coeficients are given for two mutually perpendicular directions relative to a reference axis on the structural member. They are designated as CI, and Cft, give the forces normal and transverse, respectively to the relerence plane as shown in Table 26.

Normal force, F, = C,, pd A’1 b

Transverse force, Ft = Cft pa K 1 b

Circular sections - Force coefficients for members of circular section shall be as given in Table 23 ( see also Appendix D ). Force coefficients for wires and cables shall be as given in Table 27 according to the diamater (D), the design wind speed ( f’ti) and the surface roughness.

a

a/b -

4A Values of Cr versus -I for $ 2 1

4B Values of Cc versus -: for -a < 1

‘FI~J. 4 FORCE COEFFICIENTB FOR RECTANGULAR CLAC BUILDINGS IN UNIPBRM FLO~V

39

d _-_ . ..-. -.-. --

‘IS:873(Part3)-1987

TABLE 23 FORCE COEFFICIENTS Cf FOR CLAD BUILDINGS OF UNIFORM SECTION ( ACTING IN THE DIRECTION OF WIND )

[ Clauses 6.3.2.1,6.3.2.2 and 6.3.3.2(c) ]

-i-

1 , !

-;

1 I j. 1

- i- ,

I

1, .j-

_

I-

-

Cr POX HEIOET/BEEADTH RATJO

._

- T - 1.

I

I I

I

I !

r _I.

! I

/

-1

3pro1/2j 1 5 10 f 20 ! -,- -

I

I

I’ .I. !

I

j-

2

0’7

oa

1’2

0’6

i-- I

0’8 0’9

c-5 j 0.6 i 0.6

-I--

All surfaces <6

_

Rough or with projections >6

I

0'7 0-i

I j- , o-5 , 0.5 0’5

--

0’5

See aim Apppendix c Snzooth >6 _ j

I < 10 --- > 10

0’5 I 0’5 0'7

--

0.2

1’7

1’5

I

0’2 O-2

1’0

1’0

-!

Ellipse b/d - 2

<a

>8

0.8 / 0’8

_-

0’8 u-8

o-9 1-l ’ i

i.3

0’9 I

1’1 1.3

-0

(4 r b/d = 1

r/b i= l/3

34

-- --_/___

0.8 ) 0’8

--

O-5 0’5

--

1‘0

i Ia0 ---

0’6 / 0%

0’6 0’6 ’ 0’6 -_

0.4 0.4

--

0.7 0:8

--

0.5 0’5

--

0’7

0’4

0.9

0.5

@3

0.2

- _

)_

0’4 0.5

1’3 b/d = 1 r\e - lJ6

< 10

> 10

0’8

0’5 G.6

0’4

-1.

<3

>s

0’3 I 0.3

-- i

0.2 , 0.2

0’3 i 0.3 0.3

0.2

0’5

1.0 ;

I

--

0’5 0’5 b/d = l/2 r/b = l/6

All values 0.5 0.6 0’6 0’7

-]-

t d

-n

i b/d - 2 All

d rib = l/12 values 0.9 o-9 1’1

I I! --

( Chlintrcd )

40

IS t 875 ( Part 3 ) - 1987

TABLE 23 FORCE COEFFICIENTS Ci FOR CLAD BUILDINGS OF UNIFORM SECTION ( ACTING IN THE DIRECTION OF WIND’) - Contd

P~ax SRAPE Vdb

m2;s

Cf FOR HEIGHT/BREADTH RATIO !

--I 10 20 ICC /

-

. I-

I /

.I_

2 5 p to 1;2

0.7

1

0’8 0.8 0.9

_-

0.5 0’5 0.5

1’0

_/--.-J-_-____ , I

<6 b/d = 2 - r/b - l/4

>6

I !

I

1’0 I 1’2 1 1 1’6

__...+__/-I - - _

.I-

. _

_

I

0’5 O-6 j 0’6

I

0.5

1’1

.I-

_-

I

_-

--

_ -

-I

-I-

-i-

,-

.-

- _

--

_ _

-/-

-

-

_-

_-

_-

__/_

_

-

- -

_-

/--“I

-0 r’ (10

u r/a=113 _

va

710

0’8 0.8 1’3 0’9

0.5

0’9

0.9

1’5

0’6 0.5 1

--

0.9

0’5 0'6 0.5

0.9

--

0.9

0.5

1.1 0 All -~ r/a = l/12 values 1’2 1’3 1’6

-

0’9 1.1 1’2 :‘3

1’0

1’6

1’2

---

0.5

(11

r/b = l/4 ~

711

0’9 0’7 O-7 0.8

0’4 0.4 0’4

0.8 0’8

0.5

--

12

0’4

1’0

_-

0’8 0’9

O-5

1’1

--

1.0

-I

0’8 1.4

-_

0.7 1’1 1.3 0.7

0.7

0’4

--

0.7

--

0.8 0.9 1’0 I.1

-.__

0.5

1’3

0’4

-/- _I------- 0.4 1 0’5

- I-

0.4 0.5

IS : 875 ( Part 3 ) - R987

TABLE 23 FORCE COEFFICIENTS cf FOB CLAD BUILDINGS OF UNIFORM SECTION ( ACTING IN THE DIRECTION OF WIND ) - Contd

P&AN SHAPE Vd Cr FOR HEI~ET/BREADTH RATIO

up to l/2 I 2 5 10 msls

I ’

20 cc

_----- I----

- D 1’4:z~ All values 1.2 1.2 1.2 1’4 1’6

--

0.7 -cl <12 12-sided PO1 ygon _-

512

1.1 I 1.3 0’7 1’0 0’8 0’9

- )__-

0’7 0’7 0.7 0-Y 0.8 0’9 I 1’1

I L----d----J

-l-

-0 Octagon All values

1’1 1’2 1.0 1’0 1’2 1.3 1’4

~ --

-0 Hexagan All values 1’0 l-2 1.3 1’4 1’4 ( 1’5 1’1

Structures that, because of their size and design wind velocity, are in the supercritical flow regime may need further calculation to ensure that the greatest loads do not occur at some wind speed below the maximum when the flow will be subcritical,

The coefficients are for buildings without projections, except where otherwise shown.

In this table Vdb is used as an indication of the airflow regime.

42

--- ~.____..

18:875(Part3)-1987

@6

0 14l6 2 3 L 5 6 8 106- -2 3 L 5 6 8 107 2 3 L56 81’

Fro. 5 VARIATION OF Cf WITH R, ( >3 x 10’ ) FOR CIRCULAR SECTIONS

TABLE 24 FORCE COEFFICIENTS FOR LOW WALLS OR HOARDINGS ( < 15m HIGH )

( Clause 6.3.2.3 )

t--bl I I

ABOVE GROUND h’>,O-25h’ ONE EDGE ON GRUUND

Wind normal to face

WIDTH TO HEIGHT RATIO, b/h

Wall Above Ground Wall on Ground

From 0’5 to 6 From 1 to 12 l-2

10 20 1’3

16 32 1’4

20 40 l-5

40 80 1.75

60 120 1’8

80 or more 160 or more 2’0

-

1

-

DRAG COEFFICIENT, Cf

43

IS : 875 ( Part 3 ) - 1987

SIOE ELEVATION DESCRIPTION OF SHAPE

CIRCULAR OISC

HEMISPHERICAL BOWL

HEMISPHERICAL BOWL

HEMISPHERICAL

SOLID

SPHERICAL

SOLID

06 FOR V,,O<7

O-2 FOR ‘IdO’/

FIG. 6 FORCE COEFFICIENTS FOR SOLID SHAPES-MOUNTED ON A SURFACE

TABLE 25 REDUCTION FACTOR K FOR INDIVIDUAL MEMBERS

[ Clauses 6.3.2.2 md 6.3.3.2(a) ]

I/b or l/D

Circular cylinder, subcritical Row

2 5 10 20 40 50 100 C-a

0’58 0’62 0’68 0.74 0.82 0.87 0’98 1’00

Circular cylinder, supercritical flow ( DVd 9 6ma/s )

0.80 0.80 0.82 O-90 0.98 0’99 1’00 1’00

Flat plate perpendicular to wind ( DV,j 2 6m2/s )

0.62 0’66 0.69 0.81 0.87 0’90 o-95 1’00

D I 875 ( Part 3 ) - 1987

TABLE 27 FORCE COEFFICIENTS FOR WIRES AND CABLES ( I/D = 100 )

[ Clause 6.3.3.2(d) ]

FLOW REW.IE FORCE COEFFICIENT, Cr FOR ~_--_-~-~--_---~ Smooth Moder- Fine Thick Surface ately Stranded Stranded

Smooth Cables Cables Wire

(Galvani-

cf sub a

c t iilbt =

A clrc sub -

ht =

force coefficient for subcritica) circular members as given in. Table 28 or Appendix D, force coefficient for the flat sided members as given in Table 28,

zed or Painted)

(1) (2) (3) (4) (5) DVa < 0’6 me/s - - 1.2 1.3

QVa 2 0’6 ma/s - - 0’9 1’1

Dvd < 0.6 ml/s 1’2 1’2 - -

Dvd 2 cj m’js 0.5 0.7 - -

A

effective area of subcritical circular members, effective area of flat-side& members,

+ub= &rc Bub + Amty and

Area of the frame in a

Y = supercritical flow > Ae

6.3.3.3 Singleframes - Force coefficients for

a single frame having either: a) all flat sided members, or b) all circular members in which all the

members of the frame have either: i) D va less than 6 ms/s, or

ii) DVa greater than 6 ml/s. shall be as given in Table 28 according to the type of the member, the diameter (D), the design wind speed (v,J) and the solidity ratio (+).

TABLE 28 FORCE COEFFICIENTS FOR SINGLE FRAMES

SOLIDITY FORCE COEFFICIENTS, Q, FOR

RATIO Q r-___-_--*--_____-~ Fiat-sided Circular Sections Members ~--_--~~---~-~

(1) (2) 0’1 1.9

0.2 1’0

0.3 1’7

0’4 I.7

0’5 i.6

0’75 I.6

1’00 2.0

Subcri- Super- tical flow critical flow

(DVdC6 ms/s) (Dv&% ma/s)

(3) (4) 1’2 0.7

1.2 0.8

1’2 0.8

1.1 0.8

1-l 0.8

I.5 1’4

2’0 2.0

Linear interpolation between the values is permitted.

Force coefficients for a single frame not com- plying with the above requirements shall be calculated as follows:

+ (1 - Y) + cr flat sub

where C f super = force coefficient for the super-

critical circular members as given in Table 28 or Appen- dix D,

6.3.3.4 Mu&h frame buildings - This section applies to structures having two or more. parallel frames where the windward frames may have a shielding effect upon the~frames to leeward side. The windward frame and any unshield parts of other frames shall be calculated in accordance with 6.3.3.3, but the wind load on the parts of frames that are sheltered should be multiplied by a shielding factor which is dependent upon the solidity ratio of the windward frame, the types of the members comprising the frame and the spacing ratio of the frames. The values of the shielding factors are given in Table 29.

TABLE 29 SHIELDING FACTOR q FOR MULTIPLE FRAMES

EFFECTIVE FRAME SPACIXG RATIO SorJnrTY c_--_______*-_-.40- __‘_ RATIO, fl ~0’5 1’0 2’0 * >a.0

(1) (2) (3) (4) (5) (6) 0 1.0 1’0 1’0 1’0 1’0

0.1 0’9 1.0 1.0 1.0 1’0

0.2 0.8 0.9 1’0 1’0 1’0

0’3 0’7 0.8 1’0 1’0 1’0

0’4 0.6 0’7 1’0 1.0 1’0

0’5 0’5 0.6 0’9 1’0 1’0

0.7 0.3 0.6 0.8 o-9 10

1.0 0’3 0’6 0’6 0.8 1‘0

Linear interpolation between values is permitted.

Where there are more than two frames of similar geometry and spacing, the wind load on the third and subsequent frames should be taken as equal to that on the second frame. The loads. on the various frames shall be added to obtain total load on the structure.

a) The frame spacing ratio is equal to the distance, centre to centre of the frames, beams or girders divided by the least overall dimension of the frame, beam or girder measured at right angles to the direction of the wind. For triangular framed structures or rectangular framed structures diagonal to the wind, the spacing ratio

46

b)

should be calculated from the mean distance between the frames in the direction of the wind. Effective solidity ratio, p: p = CJ for flat-sided members. @ is to be obtained from Fig. 7 for members of circular cross-sections.

0 0.1 O-2 0.3 04 05 06 0 7 0 8

SOLIDITY RATIO.9

FIG..~ EFFECTIVE SOLIDITY RATIO, p FOR ROUND SECTION MEMBERS

6.3.3.5 Lattice towers

a) Force coefficient for lattice towers of square or equilateral triangle section with flat- sided members for wind blowing against any face shall be as given in Table 30.

TABLE 30 OVERALL FORCE COEFFICIENT FOR TOWERS COMPOSED OF FLAT-SIDED MEMBERS

SOLIDITY RATIO FORGE COEEFICIENT BOR cm-_-_-.“-- s-s-7

4 Square Towers Equilateral Tri- angular Towers

(1) (2) (3) 0.1 3’8 3.1

0’2 3.3 2’7

0.3 2.8 2.3

0.4 2’3 1’9

0’5 2’1 1’5

b)

4

4

For square lattice towers with flat-sided members the maximum load, which occurs when the wind blows into a corner shall be taken as 1.2 times the load for the wind blowing against a face.

For equilateral-triangle lattice towers with flat-sided members, the load may be assu- m ed to be constant for any inclination of wind to a face.

Force coefficients for lattice towers of square section with circular members, all in the same flow regime, may be as given in Table 31.

IS t 875 ( Part 3 ) - 1987

Force coefficients for lattice towers of equilateral-triangle s’ection with circular members all in the same flow ragime may be as given in Table 32.

TABLE 31 OVERALL FORCE COEFFICIENT FOR SQUARE TOWERS COMPOSED OF

ROUNDED MEMBERS

[ Clause 6.3.3.5(d) ]

SOLIDITY RATIO OF

FORCE COEFFICIENT FOR r-----------

FRONT FACE Subcritical Flow h-- _____ --~

(Dvd < 6 mr/s) Supercritical Flow ( DVd 2 6 d/s 1

r-__*_-_y r---h Onto face

--7 Onto Onto face Onto

corner corner

(1) (2) (3) (4) ,(5) 0’05 2’4 2.5 1’1 1’2 0’1 2’2 2’3 1’2 1’3 0’2 1’9 2.1 1’3 1’6 0’3 1’7 1’S 1’4 1’6 0’4 1’6 1’9 1.4 1.6 0.5 1’4 1’9 1’4 1’6

TABLE’ 32 OVERALL FORCE COEFFICIENT FOR EQUILATERAL-TRIANGULAR TOWERS

COMPOSED OF ROUNDED MEMBERS

[ Clause 6.3.3.5(e) ]

SOLIDITY RATIO FORCE COEFFICIENT FOB OF FRONT FACE I----- ----

s+

--_-_--_-~ Subcritical Flow Supercritcial Flow (Dvd < 6 m*/s) (Dvd < 6 ms/s) c__-*-‘_~ r-__A-__y

All wind All wind directions directions

(1) !2) (3) 0’05 1’8 0.8 0’1 l-7 0.8 0.2 1’6 1’1

0’3 1’5 1’1

0’4 1.5 1’1

0’5 1’4 1’2

6.3.3.6 Tower a@rtenanccs - The wind loading on tower appurtenances, such as ladders, conduits, lights, elevators, etc, shall be calculated using appropriate net pressure coefficients for these elements. Allowance may be made for shielding effect from other elements.

7. DYNAMIC EFFECTS

7.1 General - Flexible slender structures and structural elements shall be investigated to ascertain the importance of wind induized oscillations or excitations along and across the direction of wind.

In general, the following guidelines may be ‘used for examining the problems of wind induced oscillations:

a) Buildings and closed structures with a height to minimum lateral dimension ratio of more than about 5.0. and

47

IS : 875 ( Part 3 ) - 1987

b) Buildings and closed structures whose natural frequency in the first mode -is less than 1-O Hz.

Any building or structure which does not satisfy either of the above two criteria shall be examined for dynamic effects of wind.

NOTE 1 - The fundamental time period (I) may either be established by experimental observations on similar buildings or calculated by any rational method of analysis. In the absence of such data, T may be determined as follows for multi-storeyed buildings:

4

b)

For moment .resisting frames without bracing or shear walls for resisting the lateral loads

z-=0*1 n where

n = number of storeys including basement storeys; and

For all others

== 0’09 H

d/d where

H - total height of the main structure of the building in metres, and

d = maximum base dimension of building in metrcs in a direction parallel to the applied wind force.

NOTE 2 - If preliminary studies indicate that wind-induced oscillations are likely to be rignificant, investigations should be persuade with the aid of analytical methods or, if necessary, by means oi wind tunnel tests on models.

NOTE 3 - CrossLwind motions may by due to lateral gustiness of the wind, unsteady wake flow (for example, vortex shedding ), negative aerodynamic damping or to a combination of these effects. These cross-wind motions, can become critical in the design of tall buildings/structures.

NOTE 4 - Motions in the direction of wind (known also as buffeting) are caused by fluctuating wind force associated with gusts. The excitations depend on gust energy available at the resonant frequency.

NOTE 5 - The wake shed from an upstream body may intensify motions in the direction of the wind, and may also affect crosswind motions.

NOTE 6 -The designer must be aware of the following three forms of wind induced motion which are characterized by increasing amplitude of oscillation with the increase of wind speed.

a) Galloping - Galloping is transverse oscillations of some structures due to the development of aerodynamic forces which are in phase with the motion. It is characterized by the progressively increasing amplitude of transverse vibration with increase of wind speed. The cross-section which are particularly prone to this type of excitation include the following:

i) All structures with non-circular cross-sections, such as triangular, square, polygons, as well as angles, crosses, and T-sections,

ii) Twisted cables and cables with ice encrusta- tions.

b) Flutter - Flutter is unstable oscillatory motion of a structure due to coupling between aerodynamic force and elastic deformation of the structure. Perhaps the’ most common form is oscillatory motion due to combined bending and torsion. Although oscillatory motions in each degree of frebdom may be damped, insta- bility can set in due to energy transfer from one mode of oscillation to another, and the structure is seen to execute sustained or divergent oscilla-

Cl

tions with a type of motion which is a combination of the individual modes of motion. Such energy transfer takes place when the natural frequencies of modes, taken individually, are close to each other ( ratio. being typically less than 2’0 ). Flutter can set in at wind speeds much less than those required for exciting the individual modes of motion. Long span suspension bridge decks or any member of a structure with large values of d/t ( where d is the depth of a structure or structural member parallel to wind stream and t is the least lateral dimension of a member ) are prone to low speed flutter. Wind tunnel testing is required to. determine critical flutter speeds and the likely structural response. Other types of flutter are single degree of freedom stall flutter, torsional flutter, etc.

Ovafiing- This walled structures with open ends at one or both ends such as oil storage tanks, and natural draught cooling towers in which the ratio of the diameter of minimum lateral dimension to the wall thickness is of the order of !OO or more, are prone to ovalling oscillations. These oscillations are characterized by periodic radial deformation of the hollow structure.

NATE 7 -Buildings and structures that may be subjected to serious wind excited oscillations require careful investigation. It is to be noted that wind induced oscillations may occur at wind speeds lower than the static design wind speed for the location.

NOTE 8 - Analytical methods for the response of dynamic structures to wind loading can be found in the following publications:

i) Engineering Science Data, Wind Engineering Sub-Series ( 4 volumes ), London, ESDU Inter- national.

ii) ‘Wind Engineering in the Eighties’, Construc- tion Industry Research and Information Associ- ation, 1981, London.

iii) ‘Wind Effects on Structures’ by E. Simiu and R.H. Scanlan, New York, John Wiley and Sons, 1978.

iv) Supplement to the National Building Code of Canada. 1980. NRCC, No. 17724, Ottawa, Nati- onal Research Council of Canada, 1980.

v) Wind forces on structures by Peter Sachs. Per- gamon press.

vi) Flow induced vibration by Robert D. Clevins, Van Nostrand Reinfold Co.

vii) Appropriate Indian Standards ( see 1.1.3 ).

NOTE 9 - In assessing wind loads due to such dynamic phenomenon as galloping, flutter and ovalling, if the required information is not available either in the references of Note 8 or other literature, specialist advise shall be sought, including experiments on models in wind tunnels.

7.2 Motion Due to Vortex Shedding

7.2.1 Slender Structures - For a structure, the shedding frequency, 3 shall be determined by the following formula:

where

S = Strouhal number,

v#j = design wind velocity, and b = breadth of a structure or structural

members in the horizontal plane normal to the wind direction.

48

IS : 875 ( Part 3 ) - 1987

8.2.1 Variation of Hourb Mean Wind Speed with Height - The variation of hourly mean wind speed with height shall cbe calculated as follows:

Vz = Vb h ha ks

where

P, = hourly mean wind speed in m/s, at height e;

vb = regional basic wind speed in m/s (see Fig. 1 );

kl = probability factor ( see 5.3.1 );

& = terrain and height factor ( see Table 33 ); and

A-s - topography factor ( see 5.3.3 ).

a) Circular Structures - For structures circular in cross-section:

S = 0.20 for bV’, not greater than 7, and

= 0.25 for bV, greater than 7.

b) Rectangular Structures - For structures of rectangular cross-section:

S = O-15 for all values of b V,.

NOTE 1 - Significant cross wind motions may be produced by vortex shedding if the natural frequency of the structure or structural element is equal to the frequency of the vortex shedding within the range of expected wind velocities. In such cases, further analysis should be carried out on the basis of references given in Note 8 of 7.1.

NOTE 2 - Unlined welded steel chimney stacks and similar structures are prone to excitation by vortex shedding.

NOTE 3 - Intensification of the effects of periodic vortex shedding has been reported in cases where two or more similar structures are located in close proximity. for example, at less than 20 b apart, where b is the dimension of the structure normal to the wind.

NOTE 4 - The formulae given in 7.2.1(a) and (b) are valid for infinitely long cylindrical structures. The value of Sdecreases slowly as the ratio of length to maximum transverse width decreases; the reduction being up to about half the value, if the structure is only three times higher than its width. Vortex shedding need not be considered if the ratio of length to maximum transverse width is less than 2’0.

8. GUST FACTOR ( GF ) OR GUST EFFEC- TIVENESS FACTOR ( GEF ) METHOD

8.1 Application - Only the method of calculating load along wind or drag load by using gust factor method is given in the code since methods for calculating load across-wind or other components are not fully matured for all types of structures. However, it is permissible for a designer to use gust factor method to calculate all components of load on a structure using any available theory. However, such a theory must take into account the random nature of atmospheric wind speed.

NOTE - It may be noted that investigations for various types of wind induced oscillations outlined in 7 are in no way related to tRe use of gust factor method given in 8 although the study of 7 is needed for using gust factor method.

8.2 Hourly Mean Wind - Use of the existing theories of gust factor method require a knowl- edge of maximum wind speeds averaged over one hour at a particular location. Hourly mean wind speeds at different heights in different terrains is given in Table 33.

NOTE - It must also be recognized that the ratio of hourly mean wind [ HMW ) to peak speed given in Table 33 may not be obtainable in India since extreme wind occurs mainly due to cyclones and thunderstorms, unlike in UK and Canada where the mechanism is fully developed pressure system. However Table 33 may be followed at present for the estimation of the hourly mean wind speed till more reliable values become available.

TABLE 33 HOURLY MEAN WIND SPEED FACTOR

Xs IN DIFFERENT TERRAINS FOR DIFFERENT HEIGHTS

( Cluuses 8.2 and 8.2.1 )

HEIQ~T T~RRA.IN m r--------- - ----- ---7

Category 1 Category 2 Category 3 Category 4

(1) (4 (3) up to 10 0’78 0’67

15 0.82 O-72

20 0’85 0’75

30 0’88 0’79

50 0.93 0’85

100 0’99 0.92

150 1’03 0’96

200 1.06 1’00

250 l-08 1.02

300 1’09 1.04

350 1’11 1’06

400 1’12 1.07

450 1.13 1’08

500 1’14 1’09

(4) (5) 0’50 0’24

0’55 0.24

0’59 0’24

0’64 0’34

0’70 0’45

0.79 0.57

0.81 0’64

0.88 0.68

0.91 0.72

0’93 o-74

0’95 0’77

0’97 0’79

0.98 081

o-99 0.82

8.3 Along Wind Load - Along wind load on a structure on a strip area ( A, ) at any height (2) is given by:

F - Ci A, j& G z- where

F, = along wind load on the structure at any height z corresponding to strip area &

Ct = force coefficient for the building,

A e = effective frontal area considered for the structure at height c,

Pz = design pressure at height z due to hourly mean wind obtained as 0.6 vzs ( N/ma ),

G , and is

given by:

G= 1 +gfr B (l+b)” + ‘$1

49

IS : 875 ( Part 3 ) - 1987 .

where

& = peak factor defined as the ratio of the expected peak value to the root mean value of afluctuating load, and

Y = roughness factor which is dependent on the size of the structure in relation to the ground roughness.

The, value of (gfr’ is given in Fig. 8,

B = background factor indicating a measure of slowly varying component of fluctuating wind load and is obtained from Fig. 9,

SE -e

P measure of the resonant component of the

fluctuating wind load,

S = size reduction factor ( see Fig. 10 ),

E = measure of available energy in the wind stream at the natural frequency of the structure ( see Fig. 11 ),

/3 = damping coefficient ( as a fraction of critical damping ) of the structure ( see Table 34 ), and

grr 0- d= 4 and is to be accounted only

for buildings less than 75 m high in terrain Category 4 and for buildings .less than 25 m high in terrain Cateiory 3, and is to be taken as zero in all other cases.

BUILDING HEIGHT,m

Fro 8 VALUES OF&r AND L (h)

0.8

0.6

0.01 -02 -04 .06 .l .2 .3 .L .5 .f! 1 2 6 810

CZh/L(h)

F1o.9 BACKGROUND FACTOR B

50

IS t 875 ( Part 3 ) - 1987

0.2 W $ 0.15

0 c LI

0 .!

Q lL

gJ 0.05 “, O.OL

= 0.03

‘; 0.02

2

0.01

fo L(h:/vh

Fro. 11 GUST ENERGY FACTOR, E

In figures 8 to 11,

where c, = lateral correlation constant which may

be taken as 10 in the absence of more precise load data,

Ca = longitudinal correlation constant which may be taken as 12 in the absence of more precise load data,

b = breadth of a structure normal to the

TABLE 34 SUGGESTED VALUES OF DAMPING COEFFICIENT

( Clause 8.3 )

N ATUBE 0~ STRIJCTURE DAMPING COEFFICIENT, @

(1) (2)

Welded steel structures 0’010

Bolted steel structures 0’020

Reinforced concrete structures 0’016

8.3.1 The peak acceleration along the wind direction at the top of the structure is given by the following formula:

wind stream,

h = height of a structure,

.pb = v, = hourly mean wind speed at height t, where

z== f,, = natural frequency of the structure, and

Lul) = a measure of turbulence length scale ( see Fig. 9 ).

mean deflection at the position where the acceleration is required. Other notations are same as given in 8.3.

52

APPENDIX A

( Clause 5.2 )

IS t 875 ( Part 3 ) - 1987

BASIC WIND SPEED AT 10 m HEIGHT FOR SOME IMPORTANT CITIES/TOWNS

City/Town Basic Wind S’eed ( m/s )

Agra

Ahmadabad

Ajmer

Almora

Amritsar

Asansol

Aurangabad

Bahraich

Bangalore

Barauni

Bareilly

Bhatinda

Bhilai

Bhopal

Bhubaneshwar

Bhuj

Bikaner

Bokaro

Bombay

Calcutta

Calicut

Chandigarh

Coimbatore

Cuttack

Darbhanga

Darjeeling

Dehra Dun

Delhi

Durgapur

Gangtok

Gauhati

Gaya

Gorakhpur

Hyderabad

Imphal

Jabalpur

Jaipur

Ja.mshedpur

47

39

47

47

47

47

39

47

33

47

47

47

39

39

50

50

47

47

44

50

39

47

39

50

55

47

47

47

47

47

50

39

47

44

47

47

47

47

City/ Town Basic Wind Speed ( m/s )

Jhansi 47

Jodhpur 47

Kanpur 47 Kohima 44 Kurnool 39

Lakshadweep 39 Lucknow 47 Ludhiana 47 Madras 50 Madurai 39 Mandi 39

Mangalore 39 Moradabad 47

Mysore 33 Nagpur 44 Nainital 47 Nasik 39 Nellore 50 Panjim 39 Patiala 47 Patna 47 Pondicherry 50 Port Blair 44 Pune 39 Raipur 39

Rajkot 39

Ranchi 39 Roorkee 39 R ourkela 39 Simla 39 Srinagar 39 Surat 44 Tiruchchirrappalli 47 Trivandrum 39 Udaipur 47 Vadodara 44 Varanasi 47 Vi jaywada 50 Visakhapatnam 50

53

IS a 875 ( Part 3 ) - 1987

APPENDIX B

[ Clau.se 5.3.2.4(b)(ii) ]

CHANGES IN TERRAIN CATEGORIES

B-1. LOW TO HfGH NUMBER

B-l.1 In cases of transition from a low category number ( corresponding to a low terrain roughness ) to a higher category number ( corresponding to a rougher terrain ), the velocity profile over the rougher terrain shall be determined as follows:

a) Below height h,, the velocities shall be determined in relation to the rougher terrain; and

b) Above height h,, the velocities shall be determined in relation to the less rough ( more distant ) terrain.

B-2. HIGH TO LOW NUMBER

B-2.1 In cases of transition from a more rough to a less rough terrain, the velocity profile shall be determined as follows:

a) Above height h,, the velocities shall be

b)

determined in accordance with the rougher ( more distant ) terrain; and Below height h,, the velocity shall be taken as the lesser of the following: i) that determined in accordance with the

less rough terrain, and ii) the velocity at height h, as determined.

in relation to the rougher terrain.

NOTE - Examples of determination of velocity profiles in the vicinity of a change in terrain category are shown in Fig. 12A and 12B.

B-3. MORE THAN O&E CATEGORY

B-3.1 Terrain changes involving more than one category shall be treated in similar fashion to that described in B-1 and B-2.

NOTE’- Examples involving three terrain categories are shown in Fig. 12C.

x,=FETCH,h, = HEIGHT FOR CATEGORY 4

-..,. e PROFILE FOR CATEGORY6

-----. PROFILE FOR CATEGORY 2

- DESIGN PROFILE AT A

WIND DIRECTION

CATEGORY 2

12A Determination of Velocity Profile Near a Change in Terrain Category ( less rough to more rough )

x2=FETCH, h2=HEIGHT FOR CATEGORY 2

..--..PROFILE FOR CATEGORY .4

- --- PROFILE FOR CATEGORY 2

-DESIGN PROFILE AT A I

L I I I

WIND DIRECTION

/ /

I-- A

CATEGORY L CATEGdRY 2 x2 -*

128 Determination of Velocity PioRle Near a Change in Terrain Category (more rough to less rough)

Fro. 12 VELOCITY PROFILE IN THE VICIIVITY OF A CHANGE IN TERRAIN CATEGORY - Co&

54

ISt875(Part3)-1387

q,=FETCH, h&-HEIGHT FOR CATEGORY 4

x,=FETCH, h,=HEIGHT FOR CATEGORY 1

. . . . . . . . VELOCITY PROFILE FOR CATEGORY L

---__ VELOCITY PROFILE FOR CATEGORY 3 _._. - VELOCITY PROFILE FOR CATEGORY 1

- DESIGN PROFILE

VELOCITY VELOCITY VELOCITY

12C Determination of Design Profile Involving More Than One Change in Terrain Category

FIG. 12 VELOCITY PROFILE IN THE VICINITY OF A CHANGE IN TERRAIN CATEGORY

APPENDIX C

( Clause 5.3.3.1 )

EFFECT OF A CLIFF OR ESCARPMENT ON EQUIVALENT HEIGHT ABOVE GROUND ( kJ FACTOR )

C-l. The influence of the topographic feature is considered to extend l-5 L, upwind add 2.5 Le downwind of the summit of crest of the feature where L, is the effective horizontal length of the hill depending on slope as indicated below ( SCG Fig. 13 ):

where

L = actual length of the upwind slope in the wind direction,

< - effective height of the feature, and

6 = upwind slope in the wind direction.

If the zone downwind from the crest of the feature is relatively flat ( 8 < 3” ) for a distance exceeding L,, then the feature should be treated as an escarpment. If not, then the feature should be treated as a hill or ridge. Examples of typical features are given in Fig. 13.

NOTE 1 - No difference is made, in evaluating k, between a three dimensional hill and two dimensional ridge.

NOTE 2 -In undulating terrain, it is often not possible to decide whether the local topography to the site is significant in therms of wind flow. In such cases, the average value of the terrain upwind of the site for a distance of 5 km should be taken as the base level from wind to assess the height, z, and the upwind slope 8, of the feature.

55

C-2. TOPOGRAPHY FACTOR, ks

The topography factor kB is given by the following:

ks - I+ es

where C has the following values:

Slope C

3” < 8 ( 17O 1.2 ( > z

> 170 0.36

and s is a factor derived in accordance with C-2.1 appropriate to the height, H above mean ground

level and the distance, X, from the summit or crest rektive to the effective length, LB.

C-2.1 The factor, s, should be determined from:

a) Figure 14 for cliffs and escarpments, and

b) Figure 15 for hills and ridges.

NOTE - Where the downwind alope of a hill or ridge is greater than 3’, there will be large regions of reduced acceleratioos or even shelter and it is not posrible to give general design rules to cater for these circumstances. Values of s from Fig. 15 may be used as upper bound values.

13A General Notations

WIND CREST

DOWNWIND SLOPE ,3’

136 Cliff and Escarpment

WIND CREST

13C Hill and Ridge

FIG. 13 TOPOGRAPHICAL DIMENSIONS

CREST

Is : 875 ( Part 3 ) - 1987

CREST __

UPWIND x Le

DOWNWIND 21 Le

Fro.14 FACTOR JFOR CLIFF AND ESCARPMENT

CREST CREST

0.5 1.0 1.5 2.0 2.5’

UPWIND x LI

DOWNWIND 2 LC

FIG. 15 FACTOR JFOR RIDGE AND HILL

APPENDIX D

[ Clauses 6.3.2.2, 6.3.3.2(c) and 6.3.3 3(b) ]

WIND FORCE ON CIRCULAR SECTIONS

D-1. The wind force on any object is given by:

F = Ct &AI where

ci e force coefficient,

A, P effective area of the object normal to the wind direction, and

Pa p: design pressure of the wind.

For most shapes, the force coefficient remains approximately constant over the whole range of

wind speeds likely to be encountered. However, for objects of circular cross-section, it varies considerably.

For a circular section, the force coefficient depends upon the way in which the wind flows around it and’is dependent upon the velocity and kinematic’viscosity of the wind and diameter of the section. The force coefficient is usually quoted against a non-dimensional parameter, called the Reynolds number, which takes account of the

57

IS I 875 ( Part 3 ) - 1987

veloci:y and viscosity of the flowing medium ( in this case the wind ), and the member diameter.

DVa Reynolds number, R, = - ‘I

where

D = diameter of the member,

Vd - design wind speed, and FIG. 17 WAKE IN SURERCRITICAL FLOW

y - kinematic viscosity of the air which is 146 X lO_sms s at 15°C and standard atmospheric pressure.

Since in most natural environments likely to be found in India, the kinematic viscosity of the air is fairly constant, it is convenient to use D Vd as the parameter instead of Reynolds num- bers and this has been done in this code.

The dependence of a circular section’s force coefficient or Reynolds number is due to the change in the wake developed behind the body.

At a low Reynolds number, the wake is as shown in Fig. 16 and the force coefficient is typically 1.2. As Reynolds number is increased, the wake gradually changes to that shown in Fig. 17, that is, the wake width d, decreases and the separation point, S, moves from front to the back of tbe body.

FIG. 16 WAKE IN SUBCRITICAL FLOW

As a result, the force coefficient shows a rapid drop at a critical value of Reynolds number, followed by a gradual rise as Reynolds number is increased still further.

The variation of Cr with parameter DVd is shown in Fig. 5 for infinitely long circular cylinders having various values of relative surface roughness ( t/D ) when subjected to wind having an intensity and scale of turbulence typical of built-up urban areas. The curve for a smooth cylinder ( t/D ) = 1 x 10-s in a steady air- stream, as found in a low-turbulence wind tunnel, is shown for comparison.

It can be seen that the main effect of free- stream turbulence is to decrease the critical value of the parameter D V a. For subcritical flows, turbulence can produce a considerable reduction in Cr below the steady air-stream values. For supercritical flows, this effect becomes significantly smaller.

If the surface of the cylinder is deliberately roughened such as by incorporating flutes, rivett- ed construction, etc. then the data given in Fig. 5 for appropriate value of t/D > 0 shall be used.

NOTE - In case of uncertainty regarding the value of c to be used for small roughnesses, c/D shall be ta4en a5 0’001.

58

.,


BIS is a statutory institution established under the Bureau of Indian Standards Act, 1986 to promote harmonious development of the activities of standardization, marking-and quality certification of goods and attending to.connected matters in the country.

Copyright

BIS has the copyright of all its publications. No part of these publications may be reproduced in any form without the prior permission in writing of BIS. This does not preclude the free use, in the course of implementing the standard, of necessary details, such as symbols and sizes, type or grade designations. Enquiries relating to copyright be addressed to the Director (Publication), BIS.


Amendments are issued to standards as the need arises on the basis of comments. Standards are also reviewed periodically; a standard along with amendments is reaffirmed when such review indicates that no changes are needed; if the review indicates that changes are needed, it is taken up for revision. Users of Indian Standards should ascertain that they are in possession of the latest amendments or edition by referring to the latest issue of ‘BIS Handbook’ and ‘Standards Monthly Additions’



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PATNA. PUNE. THIRUVANANTHAPURAM.

Printed at Dee Kay Printers, New Delhi, India

IS I 875 ( Part 3 ) - 1987

CONTENTS

AMENDMENT NO. 1 DECEMBER 1997 TO

IS 875 ( Part 3 ) : 1987 CODE OF PRACTICE FOR DESIGN LOADS (OTHER THAN EARTHQUAKE) FOR

BUILDINGS AND STRUCTURES

PART 3 WIND LOADS

( Second Revision )

( Page 15, Tabk 4, first column ) - Substitute

‘It ‘h - 26’ for - P CD’

( Page 40, Tablz 23, first rfolumn, first row ) - Substitute ‘See also

Appendix D’ for ‘See also Appendix C’.

( Page 47, Table 32, coZ2 ) - Substitute

‘DVd 2 6 m2/s7 for ‘Dvd 4 6 ~1~1s’.

(CED37)

Page

j 3 5

5

6

7

7

7

8

8

8

8

12

12

13

13

13

13 13 13 27 36 37

37 38 47 47 48

48 49 49 49 19

*9

Printed at Dee Kay Printers, New Delhi-110015, India. 53

54

j5

57

AMENDMENT NO. 2 MARCH 2002TO

IS S75 ( PART 3 ) :1987 CODE OF PRACTICE FORDESIGN LOADS (OTHER THAN EARTHQUAKE) FOR

BUILDINGS AND STRUCTURES

PART 3 WIND LOADS

(Second Revision )

Substitute ‘VZ’ for’ Vd’ at all places.

( Tables 5,6,7 and 8 ) — Insert the following Note at the end of each table

‘NOTE — W and L are overall length and width including overhangs, w and / aredimensionsbetweenthewalls excludingoverhangs.’

( Tables 9, 10, 11, 12, 13 and 14, first column) — Substitute the followingmatter in the Iast row for the specific values of 6 given therein:

‘for all values of (3‘

[ Page 27, clause 6.2.2.7(a)] — Insert at the end ‘downwards’.

[ Page 27, clause 6.2.2.8(a)] — Substitute ‘-O.8’~or ‘0.8’.

[ Page 27, clause 6.2.2.8(b)] — Substitute ‘-O.5’~or ‘0.5’.

( Page 27, clause 6.2.2.9) — Substitute ‘P= 0.785 D2 (Cpi - CpC)pd’ for theexisting formula.

( Page 32, Table 19) — Substitute ‘P= 0.785 D2 (WI - C@pd for the existingformula.

( Page 46, Table 27, third row) — Substitute CDVd <6 m2Ls’ fQrthe existing.

( Page 46, Table 28,CO12, second row) — Substitute ‘1.8’ for ‘1.0’.

( Page 46, clause 6.3.3.3, formula, last line) — Substitute

( Area.of the frame in a supercritical flow )Y =

Aefor the existing.

[ Page 47, clause 7.l(a), third line] — Substitute ‘or’for ‘and’.

1

...

Amend No. 2 to 1S 875 ( Part 3 ) :1987

[ Page 48, clause 7.l(b),first line ] — Delete ‘clcxs4’; ‘ ‘

( Page 48, clause 7.1, fourth and fifih line ) — Substitute ‘satisfies’ for ‘doesnot satisfy’.

( Page 55, clause C-1, second line) — Substitute ‘and’for ‘add’.

( Page 56, clause C-2, last line) — Insert ‘~,between ‘crest’ and ‘relative’.

( Page 56, Fig. 13A) — Substitute the following figure for the existing:—

WIND

r

2 A5—

.,+$)

&

‘f’/ L —x ,->

5km w-W LWW IND + w DOWNWIND

13A GeneralNotetlons

( Page 56, Fig. 13B ) — Substitute ‘Hill and Ridge’ for ‘Cliff andEscarpment’.

—

( Page 56, Fig. 13C ) — Substitute ‘Cliff and Escarpment’,for‘Ridge’.

( Page 58, clause D-1, eighth line) — Substitute ‘m2/s’~or ‘m2s’

( CED 57 )

‘Hill and

ReprographyUnir, BIS, New Delhi, India

2

IS : 875 ( Part 4 ) - 1987( Reaffirmed 1997 )

Indian Standard

CODE OF PRACTICE,FORDESIGN LOADS ( OTHER THAN EARTHQUAKE )

FOR BUILDINGS AND STRUCTURESPART 4 SNOW LOADS

(Second Revision).

Fourtll Rcprjnt OCTOBER 1997

UDC 624.042-42 : 006.7

@ Copyright 1988


NEW DELHI 110002

Gr 4 October 1988

fndian Standard

CODEOFPRACTICE

IS:875(Bart4)-1987

FORDESIGNLOADS(OTHERTHANEARTHQUAKE)

FORBUILDINGSAND STRUCTURES r.PART 4 SNOW LOADS

(Second Revision)

0. F O R E W O R D

0.1 This Indian Standard ( Part4 ) ( SecondRevision ) was adopted by the Bureau of IndianStandards on 9 November 1987, after the draftfinalized by the Structural Safety SectionalCommittee had been approved by the CivilEngineering Division Council.

0.2 A building has to perform many functionssatisfactorily. Amongst these functions are theutility of the building for the intended use andoccupancy. structural safety, fire safety; andcompliance with hygienic, sanitation, ventilationand daylight standards. The design of the build-ing is dependent upon the minimum requirementsprescribed for each of the above functions. Theminimum requirements pertaining to the structuralsafety of buildings are being covered in this Codeby way of laying down minimum design loads whichhave to be assumed for dead loads, imposed loads,wind loads, snow loads and other external loads,the structure would be required to bear. Strictconformity to loading standards recommended inthis Code, it is hoped, will not only ensure thestructural safety of the buildings which are beingdesigned and constructed in the country andthereby reduce the hazards to life and propertycaused by unsafe structures, but also eliminate thewastage caused by assuming unnecessarily heavyloadings. Notwithstanding what is stated regardingthe structural safety of buildings, the application ofthe provisions should be carried out by compe-tent and responsible structural designer who wouldsatisfy himself that the structure designed inaccordance with this code meets the desiredperformance requirements when the same iscarried out according to specifications.

0.3 This Code was first published in 1957 for theguidance of civil engineers, designers and archi-tects associated with the planning and design ofbuildings. It included the provisions for thebasic design loads ( dead loads, live loads, windloads and seismic loads ) to be assumed in thedesign of buildings. In its first revision in 1964,the wind pressure provisions were modified onthe basis of studies of wind phenomenon and itseffects on structures undertaken by the special

committee in consultation with the Indian Meteo-rological Department. In addition to this, newclauses on wind loads for butterfly type structureswere included; wind pressure coefficients forsheeted roofs, both curved and sloping, weremodified; seismic load provisions were deleted( separate code having been prepared ) and metricsystem of weights and measurements was adopted.

0.3.1 With the increased adoption of the Code,a number of comments were received on the pro-visions on live load values adopted for differentoccupancies. Simultaneously live loads surveyshave been carried out in America, Canada andother countries to arrive at realistic live loadsbased on actual determination of loading( mov-able and immovable ) in different occupancies.Keeping this in view and other developments inthe field of wind engineering, the Sectional Com-mittee responsible for the preparation of thisstandard has decided to prepare the secondrevision in the following five parts:

Part 1 Dead Loads

Part 2 Imposed Loads

Part 3 Wind Loads

Part 4 Snow Loads

Part 5 Special Loads and Load Combinations

Earthquake load is covered in IS : 1893-1984*which should be considered along with the aboveloads.

0.3.2 This part ( Part 4 ) deals with snow loadson roofs of buildings.

The committee responsible for the prepara-tion of the code while reviewing the availablesnow-fall data, felt the paucity of data on whichto make specific recommendations on the depthof ground snow load for different regions effectedby snow-fall, In due course the characteristic

*Criteria for earthquake resistant designing of strue-trues (fourth revision ).

1

IS:875(Part4)-1987

snow load on ground for different regions will ‘Basis for design of structures - Determinationbe included based on studies. of snow loads on roofs’, issued by the Interna-

0.4 This part is based on IS0 4355-198 1 ( E )tional Organization for Standardization.

1. SCOPE

1.1 This standard (Part 4) deals with snow loadson roofs of buildings. Roofs should be designedfor the actual load due to snow or for the &posedloads specified in Part 2 Imposed loads, whicheveris more severe.

NOTB - Mountainous regions in northern parts ofIndia are subjected to snow-fall.

In India, parts of Jammu and Kashmir ( BaramulahDistrict, Srinagar District, Anantnag District andLadakh District ); Punjab, Himachal Pradesh( Chamba, Kulu, Kinnaur District, Mahasu District,Mandi District, Sirmur District and Simla District );and Uttar Pradesh ( Dehra Dun District, Tehri GarhwalDistrict, Almora District and Nainital District ) experi-ence snow-fall of varying depths two to three times ina year.

2. NOTATIONS

3.

3.1

p ( Dimensionless) - Nominal values of theshape coefficients, tak-ing into account snowdrifts, sliding snow,etc, with subscripts, ifnecessary.

Ij ( in metres ) - Horizontal dimensionswith numerical sub-scripts, if necessary.

hj ( in metres ) - Vertical dimensionswith numerical sub-

. scripts, if necessary.

fii (in degrees) - Roof slope.

so (in pascals ) - Snow load on ground.

SI ( in pascals ) - Snow load on roofs.

SNOW LOAD IN ROOF (S)

The minimum design snow load on a roofarea or any other area above ground which issubjected to snow accumulation is obtained bymultiplying the snow load on ground, s, by theshape coefficient CL, as applicable to the particularroof area considered.

S=c(S0

where

s = design snow load in Pa on plan areaof roof,

p = shape coefficient ( see 4), and

so = ground snow load in Pa( 1 Pa = lN/ma ).

NOTE - Ground snow load at any place depends onthe critical combinati.m of the maximum depth of un-disturbed aggregate cumulative snow-fall and itsaverage density. In due course the characteristic snowload on ground for different regions will be includedbased on studies. Till such time the users of thisstandard are advised to contanct either Snow andAvalanches Study Establishment ( Defence Researchand Development Organization ) Manali ( HP) orIndian Meteorological Department ( IMD ), Pune inthe absence of any specific information for anylocation.

4. SHAPE COEFFICIENTS

4.1 General Principles

In perfectly calm weather, falling snow wouldcover roofs and the ground with a uniform blanketof snow and the design snow load could be consi-derd as .a uniformly distributed load. Truly uni-form loading conditions, however, are rare andhave usually only been observed in areas that aresheltered on all sides by high trees, buildings, etc.In such a case, the shape coefficient would beequal to untiy.

In most regions, snow falls are accompaniedor followed by winds. The winds will redistributethe snow and on some roofs, especially multi-level roofs, the accumulated drift load may reacha multiple of the ground load. Roofs which aresheltered by other buildings, vegetation, etc, maycollect more snow load than the ground level.The phenomenon is of the same nature as thatillustrated for multilevel roofs in 4.2.4.

So far sufficient data are not available to deter-mine the shape coefficient in a statistical basis.Therefore, a nominal value is given. A representa-tive sample of rcof is shown in 4.2. However, inspecial cases such as strip loading, cleaning of theroof periodically by deliberate heating of the roof,etc, have to be treated separately.

The distribution of snow in the directionparallel to the eaves is assumed to be uniform.

2

4.2 Shape Coefficients for Selected Types of Roofs

4.2.1 Simple Flat andMonopitch Roofs

Simple Pitched Roofs(Positive Roof Slope)*

p, = 0.8

4.2.2 Simple or Multiple Pitched Roofs(Negative Roof Slope)

Two-Span or MultispanRoofs

o*<p<3lE3&#<6

49>60*

t+.= p, =O.%

t'2~=0.8+04(~)

jL, =0*8

Pl**

pp1-6m-0

l For.asymmetrical simple Pitched roofs, each side of the roof shall be treated as me half of correspondingsymmetwal roofs.

3

Is:875(Partl)-1987

4.2.3 Simple Curved Roofs

The following cases 1 and 2 must be examined:

CASE 2

Restriction:

h<F3

a-OifB>60’

4

Is:875(Part4)-1987

4.2.4 Multilevel Roofs*

91 = 0’8

Bs = Ps + Pa

where

A - due to sliding

pw - due to wind

1, = 2ht but is restricted as follows:

SmCls<lSm

11 + f, < khPW=T -SO

with the restriction 0.8 < pw ( 4’0

where

h is in metres

so is in kilopascals ( kilonewtons per square metre )k =2kN/m8

p > 19” : ps is determined from an additional load amounting to SO percent of the maximum total load on theadjacent slope of the upper roofs, and is distributed linearly as shown on the figure.

B < 15” : ps = 0

*A more extensive formula for pw is described in Appendix A.tlf 1~ < I,. the coe5cient p is determined by interpolation between JJ, and ps.SThe load on the upper roof is calculated according to 4.2.1 or 4.2.2.

5

4.25 Complex Multilevel Roofs

c

1, - 2h1: h - 2h,: p1 - 0’8

Restriction:

Sm< I,< Urn;

Sm<b<lSm;

11 and BW ( ccl + @W ), are calculated according to 4.2.1,4.2.2 and 4.2.4.

6

I.S:875(Part4)-1987

4.2.6 Roofs with Local Projections and Obstructions

where/I is in metressO is in kilopascals (kilonewtons per square metre)k I= 2 kN/ma/I1 = 0.81=2/l

Kestrictions:0’8 < /Ia < 2-OSm41615m

4.3 Shape Coefficients in Areas Exposed to Wind

The shape coefficients given in 4.2 and Appen-dix A may be reduced by 25 percent provided thedesigner has demonstrated that the following con-ditions are fulfilled:

4

b)

The building is located in an exposedlocation such as open level terrain withonly scattered buildings, trees or otherobstructions so that the roof is exposedto the winds on all sides and is ndtlikely to become shielded in the futureby obstructions higher than the roofwithin a distance from the building equalto ten times the height of the obstructionabove the roof level;The roof does not have any significantprojections such as parapet walls whichmay prevent snow from being blown offthe roof.

NOTE - In some areas, winter climate may not beof such a nature as to produce a significant reductionof roof loads from the snow load on the ground. Theseareas are:

a) Winter calm valleys in the mountains where some-times layer after layer of snow accumulates onroofs without any appreciablewind; and

removal of snow by

b) Areas (that is, high temperature) where the maxi-mum snow load may be the result of single snow-storm,removal.

occasionally without appreciable wind

In such areas, the determination of the shape coeffi-cients shall be based on local experience with dueregard to the likelihood of wind drifting and sliding.

5. ICE LOAD ON WIRES5.1 Ice loads are required to be taken into accountin the design of overhead electrical-transmissionand communication lines, over-head contact linesfor electric traction, aerial masts and similarstructures in zones subjected to ice formation.The thickness of ice deposit alround may be takento be between 3 and 10 mm depending upon thelocation of the structure. The mass density ofice may be assumed to be equal to O-9 g/cm”.While considering the wind force on wires andcables, the increase in diameter due to ice forma-tion shall be taken into consideration.

7

IS:875(Part4)-1987

A P P E N D I X A

( Clauses 42.4 and 4.3 )

SHAPE COEFFICIENTS FOR MULTILEVEL ROOFS

A more comprehensive formula for the shape coefficient for multilevel roofs than thatgiven in 4.2.4 is as follows:

-- WIN0OIRECTIONS

c

Pr -1+ + ( ml iI + mI 1, )( 1, - 2 h )

Cl = 0’8

i,=hh

fh and I being in metres)

Restriction :

whereso is in kilopascals (kilonewtons per square metre)k is in newtons per cubic metreI,< ISmValues of m, ( mr ) for the higher ( lower ) roof depend on its profile and are taken as equal to:

0.5 for plane roofs with slopes @ < 20’ and vaulted roofs with f< +-

0’3 for plane roofs with slopes p > 20” and vaulted roofs with f >$

The coefficients m, and ma may be adjusted to take into account conditions for transfer of snow on the roofsurface ( that is, wind, temperature, etc. ).

NOTE - The other condition of loading also shall be tried.



Copyright

BIS has the copyright of all its publications. No part of these publications may be reproduced in any formwithout the prior permission in writing of BIS. This does not preclude the free use, in the course ofimplementing the standard, of necessary detaik, such as symbols and sizes, type or grade designations.Enquiries relating to copyright be addressed to the Director (Publication), BIS.


Amendments are issued to standards as the need arises on the basis of comments. Standards are also reviewedperiodically; a standard along with amendments is reaffirmed when such review indicates that no changes areneeded; if the review indicates that changes are needed, it is taken up for revision. Users of Indian Standardsshould ascertain that they are in possession of the latest amendments or edition by referring to the latest issueof ‘BIS Handbook’ and ‘Standards Monthly Additions’.



BUREAU OF INDIAN STANDARDSHeadquarters:

Manak Bhavan, 9 Bahadur Shah Zafar Marg, New Delhi 110002Telephones: 323 0131,323 33 75,323 94 02

Regional Offices:


Telephone

C e n t r a l : Manak Bhavan, 9 Bahadur Shah Zafar MargNEW DELHI 110002

Eastern :

Northern :

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{832 92 95,832 78 58832 78 91,832 78 92

Printed by Reprography Unit, BIS, New Delhi

IS : 875 ( Part 5 ) - 1997 ( Reeed 1997 )

Indian Standard

CODE OF PRACTICE FOR DESIGN LOADS (OTHER THAN EARTHQUAKE)

FOR BUILDINGS AND STRUCTURES

PART 5 SPECIAL LOADS AND COMBINATIONS

( Second Revision )

Fourth Reprint NOVEMBER 1997

UDC 624'042:006'76

BURRAU MANAK

IS : 875 ( Part 5 ) - 1987

Igdian Standard

CODE OF PRACTICE F6R DESIGN LOADS (OTHER THAN EARTHQUAKE)


PART 5 SPECIAL LOADS AND LOAD COMBINATIONS

( Second Revision )

Structural Safety Sectional Committee, BDC 37

Chqirman

BBIQ DE L. V. RAYAKRI~~NA

MNl?lbrrt

DR K. G. BHATIA

SHBI M. S. BHATIA

SHEI N. K. BEATTACEABYA

R~prcssnting

Engineer-in-Chief’s Branch, Army Headquarters, New Delhi

Bharat Heavy Electricals Limited, Corporate Research Hyderabad

& Development Division,

In perronal capacity ( A-2136, Safdarjang Enclave, New Delhi )

Engineer-in-Chief’s Branch, Army Headquarters, New Delhi

SHBI S. K. MALHOTI~A [ Allsraals 1 DE S. C. CHAKRABARTI

SHBI A. DAT~A ( Alfernate ) CHIEF ENQINEEB ( ND2 ) II

STJPERINTBNDINQ SURVEYOR OF WOBKE ( NDZ ) II ( Altsrnats 1

DE P. DAYABATNAM DB A. S. R. SAI ( Altarnats )

D~UTY MUNICIPAL COYMISSI- ONpa ( ENQo )

den;tr~rk~t$lding Research Institute ( CSIR ),

Central Public Works Department, New Delhi

Indian Institute of Technology, Kanpur

Municipal Corporation of Greater Bombay, Bombay

CITY ENQINEI~R ( Altern& ) DIBEOTOR ( CMDD-I ) Central Water Commission, New Delhi

DEPUTY DIBEC~O~ ( CMDD-I ) ( Altcmats ) MAJ-Gm A. M. GOQLEKAB

PBO~ D. N. TBIKHA ( Altmnatr j Institution of Engineers ( India ), Calcutta

( Continurd on page 2 )

0 coplright 1988


This publication is protected under the Zndian Copyright Act ( XIV of 1957 ) and reproduction in whole or in part by any means except with written permission of the publisher shall be deemed to be an infringement of copyright under the said Act.

IS : 875 ( Part 5 ) - 1987

( Continasdfrom @gc 1 )

Members Rep.wnting

S~nr A. C. GWPTA Nati;: DzIymal Power Corporation Ltd,

Snap P. SEN GUPTA StewaFts and Lloyda of India Ltd, Calcutta Soar M. M. Grtosn ( Aft~r~k )

SHBI G. B. JAHAQIRDAR National Industrial Development Corporation Ltd, New Delhi

J o I N T DIRECTOR STANDARDS Ministry of Railways (B&S ), CB

Sxsr S. P. JO~HI Tata Consulting Engineers, New Delhi SHRI A. P. MULL ( Alternate )

SHBI S. R. KTJLKARNI M. N. Dastur & Co, Calcutta Saal S. N. PAL ( Alternate )

SEW H. N. MISHBA Forest Research Institute and Colleges, Debra Dun

SHBI R. K. PUNEANI ( Alternate ) SHRI T. K. D. MUNSHI Engineers India Ltd, New Delhi DR C. RAJKU~A~ National Council for Cement & Building

Materials, New Delhi Da M. N. KESHWA RAO Struc;;;iaxrgineering Research Centre ( CSIR 1.

SHBI M. V. DHABAIVEEPATEY ( Altcrnafu ) SHRI T. N. SUBBA RAO Gammon India Ltd, Bombay

DR S. V. LONEAR ( Alkrnafr ) SBEI P. K. RAY Indian Engineering Association, Calcutta

SHRI P. K. MUKHERJEE ( Altcrnofe ) SHRI S. SEETEAR~MAN Ministry of Surface Transport ( Roads Wing ),

New Delhi SHRI S. P. CEAKRABORTY \ Alternate )

Srrnr M. C. SHARMA Indian Meteorological Department, New Delhi SHRI K. S. SRINIVAYAN National Buildings Organization, New Delhi

SHLU A. K. LAL ( Altcrnafc) SHRI SUSHIL Knri~ National Building Construction Corporation Ltd,

New Delhi Snnr G. RAMAN. Director General, BIS ( Ex-o&io Mmbcr )

Director ( Civ’Engg )

SHRI B. R. NARAYANAPPA Deputy Director ( Civ Engg ), BIS

( Conlinud on page 18 )

2

IS t 875 ( Part 5 ) - 1987

Indian Standard

CODE OF PRACTICE FOR DESIGN LOADS (OTHER THAN EARTHQUAKE)


PART 5 SPECIAL LOADS AND LOAD COMBINATIONS

( Second Revision )

0. FOREWORD

0.1 This Indian Standard ( Part 5 ) ( Second Revision ) was adopted by the Bureau of Indian Standards on 3 1 August 1987, after the draft finalized by the Structural Safety Sectional Committee had been approved by the Civil Engineering Division Council.

0.2 A building has to perform many functions satisfac orily. Amongst these functions are the utility of the building for the intended use and occupancy, structural safety, fire safety; and compliance with hygienic, ganitation, ventilation and day light standards. The design of the building is dependent upon the minimum requirements prescribed for each of the above functions. The minimum requirements pertaining to the structural safety of buildings are being covered in this code by way of laying down minimum design loads which have to be assumed for dead loads, imposed loads, snow loads and other external loads, the structure would be required to bear. Strict conformity to loading standards recommended in this code, ‘It is hoped, will not only ensure the structural safety of the buildings which are being designed and constructed in the country and thereby reduce the hazards to life and property caused by unsafe structures, but also eliminate the wastage caused by assuming unnecessarily heavy loadings. Notwithstanding what is stated regarding the structural safety of buildings, the application of the provisions should be carried out by com- petent and responsible structural designer who would satisfy himself that the structure designed in accordance with this code meets the desired performance requirements when the same is carried out according to specifications. 0.3 This standard code of practice was first published in 1957 for the guidance of civil engineers, designers and architects associated with planning and design of buildings. It included the provisions for basic design

3

IS t 875 ( Part 5 ) - 1987

loads ( dead loads, live loads, wind loads and seismicloads ) to be assumed in the design of buildings. In its first revision in 1964, the wind pressure provisions were modified on the basis of studies of wind phenomenon and its effects on structures, undertaken by the special committee in consultation with the Indian Meteorological Department. In addition to this, new clauses on wind loads for butterfly type structures were included; wind pressure coefficients for sheeted roofs both curved and sloping were modified; seismic load provisions were deleted ( separate code having been prepared ) and metric system of weights and measurements was adopted.

0.3.1 With the increased adoption of the code, a number of comments were received on the provisions on live load values adopted for different occupancies. Simultaneously live load surveys have been carried out in America, Canada and other countries to arrive at realistic live loads based on actual determination of loading ( movable and immovable ) in different occupancies. Keeping this in view and other developments in the field of wind engineering, the committee responsible for the preparation of the standard decided to prepare second revision in the following five parts:

Part 1 Dead loads

Part 2 Imposed loads Part 3 Wind loads Part 4 Snow loads Part 5 Special loads and load combinations.

Earthquake load is covered in a separate standard, namely IS : 1893 1984* which should be considered along with the above loads.

0.3.2 This code ( Part 5 ) deals with loads and load effects ( other than those covered in Parts 1 to 4, and seismic loads ) due to temperature changes, internally generating stresses ( due to creep, shrinkage, differential settlement, etc ) in the building and its components, soil and hydrostatic pressure, accidental loads, etc. This part also includes guidance on load combinations.

0.4 The code has taken into account the prevailing practices in regard to loading standards followed in this country by the various municipal authorities and has also taken note of the developments in a number of countries abroad. In the preparation of this code, the following national standards have been examined:

a) National Building Code of Canada ( 1977 ) Supplement No. 4. Canadian Structural Design Manual.

*Criteria for earthquake resistant design of structures ( third renision ).

4

b)

4

4

I& : 835 ( Part 5 ) - 1987

DS 410-1983 Code of practice for loads for the design of structures. Danish Standards Institution. NZS 4203-1976 New Zealand Standard General structural design and design loading for building. Standards Association of New Zealand.

ANSI A 58.1-1982 American Standard Building code requirements for minimum design loads in buildings and other structures.

i. SCOPE

1.1 This code ( Part 5 ) deals with loads and load effects due to temperature changes, soil and hydrostatic pressures, internally generating stresses ( due to creep, shrinkage, differential settlement, etc ), accidental loads etc, to be considered in the design of buildings as appropriate. This part also includes guidance on load combinations. The nature of loads to be considered for a particular situation is to be based on engineering judgement.

2. TEMPERATURE EFFECTS

2.1 Expansion and contraction due to changes in temperature of the materials of a structure shall be considered in design. Provision shall be made either to relieve the stress by provision of expansion/contraction joints in accordance with IS : 3414-1968* or design the structure to carry additional stresses due to temperature effects as appropriate to the problem.

2.1.1 The temperature range varies for different regions and under different diurnal and seasonal conditions. The absolute maximum and minimum temperature which may be expected in different localities in the country are indicated in Fig. 1 and 2 respectively. These figures may be used for guidance in assessing the maximum variations of temperature.

2.1.2 The temperatures indicated in Fig. 1 and 2 are the air temperatures in the shade. The range of variation in temperature of the building materials may be appreciably greater or less than the variation of air temperature and is influenced by the condition of exposure and the rate at which the materials composing the structure absorb or radiate heat. This difference in temperature variations of the material and air should be given due consideration.

2.1.3 The structural analysis must take into account: (a) changes of the mean ( through the section ) temperature in relation to the initial temperature ( st ), and (b) the temperature gradient through the section,

*Code of practice for design and installation of joints in buildings.

5

fS t 835 ( Part 5 ) - 19&t

The territorial waterr of India extend into the sea to a distance of twelve nautical milar measllred from the appropriate base line.

Based upon Survey of India map with the permission of the Surveyor General of India.

~0 Government of India Copyright 1993

Responsibility for the correctness of internal details rests with the publishers,

FIG. 1 CHART SHOWING HIGHEST MAXIMUM TEMPERATURE

6

IS I 875 ( Part 5 ) - 1987

60 ?2 76 60 66 66 92 %

6 I ,/.s \.

I \ I I MAP OF INDIA

\ ‘,. 1

The territorial waters of India extend into the sea to a distance of twelve nautical miles measured from the appropriate base line.

Baaed upon Survey of India map with the permission of the Surveyor General of India.

Q Government of India Copyright 1993

Responsibility for the correctness of internal details rests with the publishers.

Fxo. 2 CHART &~Y,v~N~ LOWEST MINIMUM TEMPERATURE

7

IS : 875 (. Part 5 ) - 1981

2.1.3.1 It should be borne in mind that the changes of mean temperature in relation to the initial are liable to differ as between one structural element and another in buildings or structures, as for example, between the external walls and the internal elements of a building. The distribution of temperature through section of single-leaf structural elements may be assumed linear for the purpose of analysis.

2.1.3.2 The effect of mean temperature changes tl, and ts, and the temperature gradients u1 and vs in the hot and cold seasons for single-leaf structural elements shall be evaluated ori the basis of analytical principles.

Nom 1 - For portions of the structure below ground level, the variation of temperature is generally insignificant. However, during the period of construction when the portions of the structure are exposed to weather elements, adequate provision should be made to encounter adverse effects, if any.

NOTE 2 - If it can be shown by engineering principles, 0; if it is known from experience, that neglect of some or all the effects of tern erature do not affect the structural safety and rerviceability, they need not be cons~ 3 ered in design.

3. HYDROSTATIC AND SOIL PRESSURE

3.1 In the design ofstructures or parts of structures below ground level, such as retaining walls and ‘other walls in basement floors. the pressure exerted by soil or water or both shall be duly accounted for on the basis of established theories. Due allowance shall be made for possible surcharge from stationary or moving loads. When a portion or whole of the soil is below the free water surface, the lateral earth pressure shall be evaluated for weight of soil diminished by buoyancy and the full hydrostatic pressure.

3.1.1 All foundation slabs and other footings subjected to water pressure shall be designed to resist a uniformly distributed uplift equal to the full hydrostatic pressure. Checking of overturning of foundation under submerged condition shall be done considering buoyant wei ght of foundation.

3.2 While determining the lateral soil pressure on column like structural members, such as pillars which rest in sloping soils, the width of the member shall be taken as follows ( see Fig. 3 ):

Actual Width of Member Ratio of Effective Width to Actual Width

Less than O-5 m 3-o

Beyond 0.5 m and up to 1 m 3.0 to 2.0

Beyond 1 m 2-o

The relieving pressure of soil in front of the structural member concerned may generally not be taken into account.

8

IS : 875 ( Part 5 ) - 1987 -f 2b TO 3b

c

Fro. 3 SKETCH SHOWING EFFECTIVE WIDTH OF PILLAR FOR CALCULATINO SOIL PRESSURE

3.3 Safe guarding of structures and structural members against over-tum- ing and horizontal sliding shall be verified. Imposed loads having favot+ able effect shall be disregarded for the purpose. Due consideration shall lr~z~t;;; to the possibility of soil being permanently or temporarily

4. FATIGUE

4.1 General - Fatigue cracks are usually initiated at points of high stress concentration. These stress concentrations may be caused by or associated with holes ( such as bolt or rivet holes in steel structures ), welds including stray or fusions in steel structures, defects in materials, and local and general changes in geometry of members. The cracks usually propogate if loading is continuous.

Where there is such loading cycles, sudden changes of shape of a member or part of a member, specially in regions of tensile stress and/or local secondary bending, shall be avoided, Suitable steps shall be taken to avoid critical vibrations due to wind and other causes.

4.2 Where necessary, permissible stresses shall be reduced to allow for the effects of fatigue. Allowance for fatigue shall be made for combinations of stresses due to dead load and imposed load. Stresses due to wind and earthquakes may be ignored when fatigue is being considered unless otherwise specified in the relevant codes of practice.

9

18:875(Part5)-1687

Each element of the structure shall be designed for the number of stress cycles of each magnitude to which it is estimated that the element is liable to be subjected during the expected life of the structure. The number of cycles of each magnitude shall be estimated~ in the light of available data regarding the probable frequency of occurrence of each type of loading.

NOTB - Apart from the general observations made herein the code is unable to provide any precise guidance in estimating the probablistic behaviour and response of structures of various types arising out of repetitive loading approaching fatigue conditions in structural members, joints, materials, etc.

5. STRUCTURAL SAFETY DURING CONSTRUCTION

5.1 All loads required to be carried by the structures or any part of it due to storage or positioning of construction materials and erection equipment including all loads due to operation of such equipment, shall be considered as erection loads. Proper provision shall be made, including temporary bracings to take care of all stresses due to erection loads. The structure as a whole and all parts of structure in conjunction with the

temporary bracings shall be capable of sustaining these erection loads without exceeding the permissible stresses specified in respective codes of practice. Dead load, wind load and such parts of imposed load as would be imposed on the structure during the period of erection shall be taken as acting together with erection loads.

6. ACCIDENTAL LOADS

6.0 General-The occurrence of accidental loads with a significant value, is unlikely on a given structure over the period oftime under consideration, and also in most cases is of short duration. The occurrence of an accidental load could in many cases be expected to cause severe consequences unless special measures are taken:

The accidental loads arising out of human action include the following:

a) Impacts and collisions, b) Explosions, and c) Fire.

Characteristic of the above stated loads are that they are not a come- quence of normal use and that they are undesired, and that extensive efforts are made to avoid them. As a result, the probability of occurrence of an accidental load is small whereas the consequences may be severe.

10

IS: 875 (Parts)- 1987

The causes of accidental loads may be:

a) inadequate safety of equipment ( due to poor design or poor maintenance ); and

b) wrong operation ( due to insufficient teaching or training, indis- position, negligence or unfavourable external circumstances ).

In most cases, accidental loads only develop under a combination of several unfavourable occurrence. In practical applications, it may be ncces- sary to neglect the most unlikely loads. The probability of occurrence of accidental loads which are neglected may differ for different consequences of a possible failure. A data base for a detailed calculation of the probability will seldom be available.

NOTE - Dcfcrmination of Accidsrrtal Loads - Types and magnitude of accidental loads should preferably be based on a risk analysis. The analysis should consider all factors influencing the magnitude of the action, including preventive measures for accidental situations. Generally, only the principal load bearing system need be designed for relevant ultimate limit statea.

6.1 Impacts and Collisions

6.1.1 General - During an impact, the kinetic impact energy has to be absorbed by the vehicle hitting the structure and by the structure itself. In an accurate analysis, the probabihty of occurrence of an impact with a certain energy and the deformation characteristics of the object hitting the structure and the structure itself at the actual place nhust be considered. Impact energies for dropped objects should be based on the actual loading capacity and lifting height.

Common sources of impact are:

a) vehicles;

b) dropped objects from cranes, fork lifts, etc;

c) cranes out of control, crane failures; and

d) flying fragments.

The codal requirements regarding impact from vehicles and cranes are given in 6.1.2 and 6.1.3.

6.1.2 Collisions Between Vehicles and Structural Elements - In road tra&z, the requirement that a structure shall be able to resist collision may be assumed to be fulfilled if it is demonstrated that the structural element is able to stop a fictitious vehicle, as described in the following. It is assumed that the vehicle strikes the structural element at height of 1.2 m in any possible direction and at a speed of 10 m/s ( 36 km/h ).

11

IS : 875 ( Part 5 ) - 1987

The fictitious vehicle shall be considered to consist of two masses ml and ma which during compression of the vehicle produce an impact force increasing uniformly from zero, corresponding to the rigidities Cr and Cs. It is assumed that the mass ml is breaked completely before the braking of mass m, begins.

The following numerical values should be used:

ml = 400 kg, Cr = 10 000 kN per m the vehicle is compressed.

ms = 12 no0 kg, C’s = 300 kN per m the vehicle is compressed.

NOTE - The described fictitious collision corresponds in the case of a non-elastic structural element to a maximum static force of 630 kN for the mass ml and 600 kN for the mass ms irrespective of the elasticity. assume the static force to be 630 kN.

It will, therefore, be on the safe side to

In addition, braking of the mass ml will result in an impact wave, the effect of which will depend to a great extent on the kind of structural element concerned. Consequently, it will not always be sufficient to design for the static force.

6.1.3 Safe0 Railings - With regard to safety railings put up to protect structures against collision due to road traffic, it should be shown that the railings are able to resist on impact as described in 6.1.2.

NOTE - When a vehicle collides with safety railings, the kinetic energy of the veh+e will be absorbed in part by the deformation of the railings and, in part by the deformation of the vehicle. The part of the kinetic energy which the railings should be able to absorb without breaking down may be determined on the basis of the assumed rigidity of the vehicle during the compression.

6.1.4 Crane Impact Load on BuJer Stab - The basic horizontal load Py ( tonnes ), acting along the crane track produced by impact of the crane on the buffer stop, is calculated by the following formula:

where V-

F =

speed at which the crane is travelling at the moment of impact ( assumed equal to half the nominal value ) (m/s>; maximum shortening of the buffer, assumed equal to 0.1 m for light duty, medium-duty and heavy-duty cranes with flexible load suspension and loading capacity not exceeding 50 t, and O-2 m in every other cranes; and

M - the reduced crane mass (t.s*/m); and is obtained by the formula:

M a- ; [++ (4 + Q) -Qq

12

IS z 875 ( Part 5 ) - 1987

where

g = acceleration due to gravity ( 9.81 m/s* ); Ph = crane bridge weight (t);

Pt = crab weight (t); k = a coefficient, assumed equal to zero for cranes with flexible

load suspension and equal to one for cranes with rigid suspension;

Q = crane loading capacity (t); Lk = crane span (m); and

1 = nearness of crab (m).

6.2 Explosions

6.2.1 General - Explosions may cause impulsive loading on a structure. The following types of explosions are particularly relevant:

a) Internal gas explosions which may be caused by leakage of gas piping ( including piping outside the room ), evaporation from volatile liquids or unintentional evaporation from surface material ( for example, fire );

b) Internal dust explosions; c) Boiler failure; d) External gas cloud explosions; and e) External explosions of high-explosives ( TNT, dynamite ).

The coda1 requirement regarding internal gas explosions is given in 6.2.2.

6.2.2 Explosion Efect in Closed Rooms - Gas explosion may be caused, for example, by leaks in gas pipes ( inclusive of pipes outside the room ), evaporation from volatile liquids or unintentional evaporation of gas from wall sheathings ( for example, caused by fire ).

NOTE 1 - The effect of explosiona depends on the exploding medium, the concentration of the explosion, the shape of the room, possibilities of ventilation of the explosion. and the ductility and dynamic properties of the structure. In rooms with little possibility for relief of the pressure from the explosion, very large pressures may occur.

Internal overpressure from an internal gas explosion in rooms of sizes compara- ble to residential rooms and with ventilation areas consisting of window glass breaking at a pressure of 4 kN/m’ ( 3-4 mm machine made glass ) may be calculated from the following method:

a) The overpressure is assumed to depend on a factor A/V, where A is the total window area in m’, V is the volume in m* of the room considered.

13

18:875(PartS)-1387

b) The internal prersure is assumed to act simultaneously upon all walls and Room in one closed room.

c) The action q. may be taken M static action.

If account ir taken of the time curve of action, the following ( Fig. 4 ) rchematic correqondence between pressure and time is arrumed, where 11 is the time from the atart of combustion until maximum prerrure ia reached, and f, is the &me from maximum pressure to the end of comburtion. For 11 and t,. the most unfavourable valuer rhould be chosen in relation to the dynamic proper&a of the structures. However, the valuer should be chosen within the intervals as given in Fig. 5.

Noxut 2 - Figure 4 is based on tertr with gar explosions in room corresponding to ordinary residential flats and rhould, therefore, not be applied to considerably different conditions. The figure corresponds to an explosion caurpd by town gas and it might therefore, be somewhat on the safe aide in rooms where there is only the poaSbility of gaKI with a lower rate of combustion.

The prenure may he applied solely in one room or in more rooma at the same time. In the latter case, all room8 are incorporated in the volume V. Only windows or other similarly weak and light weight structural clementr may be taken to be ventilation areaa even through certain limited structural parts break at pressures less than qO.

Figure 4 is given purely BS guide and probability of occurrence of an explosion should be checked in each case using appropriate values.

6.3 Vertical Load on Air Raid Shelters

6.3.1 Characteristic Values - As regards buildings in which the individual floors are acted upon by a total characteristic imposed action of up to 5.8 kN/ma, vertical actions on air raid shelters generally locared below ground level, for example, basement, etc, should be considered to have the following characteristic values:

a) Buildings with up to 2 storeys 28 kN/m*

b) Buildings with 3 to 4 storeys 34 kN/m*

c) Buildings with more than 4 storeys 41 kN/m*

d) Buildings of particularly stable construction 28 kN/ms irrespective of the number of storeys

In the case of buildings with floors that are acted upon by a characteristic imposed action larger than 5.0 kN/m*, the above values should be increased by the difference between the average imposed action on all storeys above the one concerned and 5-O kN/m*.

NOTE 1 - By storeys it is understood, every utilizable storey above the shelter,

NOTE 2 - By buildings of a particular stable construction it is understood, build- inFs in which the load-bearing atructurea are made from reinforced in-situ concrete,

14

IS : 875 ( Part 5 ) - 1987

A -1 -m V

Flo.-4 SKETCH SHOWING RELATION B-N PRESSURE AND TIME

e IkN/m2) t

FICL 5 SKETCH SHOWING TIME INTERVAL AND PRESSURE

6.4 Fire

6.4.1 General - Possible extraordinary loads during a fire may be considered as accidental actions, Examples are loads from people along escape routes and loads on another structure from structure failing because of d tie.

6.4.2 Thermal Efect During Fire - The thermal effect during fire may be determined from one of the following methods:

a) Time-temperature curve and the required fire resistance ( minutes ), or

b) Energy balance method.

If the thermal effect during fire is determined from energy balance method, the fire load is taken to be:

Q = 12tb

15

1s : 875 ( Part 5 ) - 1987

where q = fire action ( K J per m* floor ), and

tb = required fire resistance ( minutes ) ( see IS : 1642-1960* ).

NOTE - The fire action is defined as the total quantity of heat produced by complete combustion of all combustible material in the fire compartment, inclusive of stored goods and equipment together with building structures and building materials.

7. OTHER LOADS

7.1 Other loads not included in the present code such as special loads due to technical process, moisture and shrinkage effects, etc, should be taken into account where stipulated by building design codes or established in accordance with the performance requirement of the structure.

8. LOAD COMBINATIONS

8.0 General - A judicious combination of the loads ( specified in Parts 1 to 4 of this standard and earthquake ), keeping in view the probability of:

a) their acting together, and b) their disposition in relation to other loads and severity of stresses

or deformations caused by combinations of the various loads is necessary to ensure the required safety and economy in the design of a structure.

8.1 Load Combinations - Keeping the aspect specified in 8.8, the various loads should, therefore, be combined in accordance with thestipulations in the relevant design codes. In the absence of such recommendations, the following loading combinations, whichever combination produces the most unfavourable effect in the building, foundation or structural member concerned may be adopted ( as a general guidance ). It should also be recognized in load combinations that the simultaneous occurrence of maximum values of wind, earthquake, imposed and snow loads is not likely,

a) DL b) DL+IL c) DLf WL d) DL+EL e) DL+TL f) DL+IL+ WL g) DL+IL+EL

*Code of practice for safety of buildings ( general ) : Materials and details of construction.

16

IS : 875 ( Part 5 ) - 1987

h) DL+ IL+ 71,

.i) DLi- WL-t_ TL k) DL+EL+ 7-L

m) DL+ILfWL+TL

n) DL+IL+EL+TL

( DL = dead load, IL = imposed load, WL = wind load, EL = earthquake load, IL = temperature load ).

NOTE 1 - When snow load is present on roofs, replace imposed load by snow load for the purpose of above load combinations.

NOTE 2 - The relevant design codes shall be followed for permissible stresses when the structure is -designed by working stress method and for partial safety factors when the structure is designed by limit state design method for each of the above load combinations.

NOTE 3 - Whenever imposed load (IL) is combined with earthquake load (EL), the appropriate part of imposed load as specified in IS : 1893- 1984f should be used both for evaluating earthquake effect and for combined load effects used in such combination.

NOTE 4- For the purpose of stability of the structure as a whole against overturning, the restoring moment shall he not less than 1’2 times the maximum overturning moment due to dead load plus 1’4 times the maxrmum overturning moment dlle to imposed loads. In cases where dead load provides the restoring moment, only 0.9 times the dead load shall be considered. The restoring moments due to imposed loads shall be ignored.

NOTE 5 - The structure shall have a factor against sliding of not less than 1’4 under the most adverse combination of the applied loads/forces. In this case, only 0’9 times the dead load shall be taken into account.

NOTE 6 -‘Where the bearing pressure on soil due to wind alone is less than 25 percent of that due to dead load and imposed load, it may be neglected in design. Where this exceeds 25 percent foundation may be so proportioned that the pressure due to combined effect of dead load, imposed load and wind load does not exceed the allowable bearing pressure by more than 25 percent. When earthquake effect is included, the permissible increase is allowable bearing pressure in the soil shall be in accordance with IS : 1893-1984*.

Reduced imposed load (IL) specified iti. Part 2 of this rtandard for the design of supporting structures should not be applied in combination with earthquake forces.

NOTE 7 - Other loads and accidental load combinations not included should be dealt with appropriately.

NOTE 8 - Crane load combinations are covered under Part 2 of this standard ( see 6.4 of Part 2 of this standard ).

*Criteria for earthquake resrstant design of structures (jourth rsuision ).

17

IS : 875 C Part 5 ) - 1987

Panel on Loads ( Other than Wind Loads ), BDC 37 : P3

Convener Repesenting

SHRI T.N. SUBBARAO Gammon India Limited, Bombay DR S. V. LONKAR ( Altcrnafr )

Members SHRIS. R. E(ULEARN1 SHRI M. L. MEH~A

M. N. Dastur 6 Co Ltd, Calcutta Metallurgical & Engineering Consultants ( India )

Ltd, Ranchi SHRI S. K. DATTA ( Alternate )

SHRI T. V. S. R. APP~ RAO Structural Engineering Research Centre, CSIR Campus, Madras

SHRI NAGESH R. DYER (Ahmfe ) SARI C. N. SRINIVASAN C. R. Narayana Rao, Madras SUPERINTENDIXQ EXQINEER ( D ) Central Public Works Department ( Central

Designs Organization ), New Delhi EXECUTIVE ENGINEER ( D ) VII ( AIternuta )

DR H. C. VISVESVARAYA National Council for Cement and Building Materials, New Delhi


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